Follows up JuliaLang#44708 -- in that PR I missed the most obvious optimization
opportunity, i.e. we can safely eliminate `isdefined` checks when all
fields are defined at allocation site.
This change allows us to eliminate capturing closure constructions when
the body and callsite of capture closure is available within a optimized
frame, e.g.:
```julia
function abmult(r::Int, x0)
    if r < 0
        r = -r
    end
    f = x -> x * r
    return @inline f(x0)
end
```
```diff
diff --git a/_master.jl b/_pr.jl
index ea06d865b75..c38f221090f 100644
--- a/_master.jl
+++ b/_pr.jl
@@ -1,24 +1,19 @@
 julia> @code_typed abmult(-3, 3)
 CodeInfo(
-1 ── %1  = Core.Box::Type{Core.Box}
-│    %2  = %new(%1, r@_2)::Core.Box
-│    %3  = Core.isdefined(%2, :contents)::Bool
-└───       goto #3 if not %3
+1 ──       goto #3 if not true
 2 ──       goto #4
 3 ──       $(Expr(:throw_undef_if_not, :r, false))::Any
-4 ┄─ %7  = (r@_2 < 0)::Any
-└───       goto #9 if not %7
-5 ── %9  = Core.isdefined(%2, :contents)::Bool
-└───       goto #7 if not %9
+4 ┄─ %4  = (r@_2 < 0)::Any
+└───       goto #9 if not %4
+5 ──       goto #7 if not true
 6 ──       goto #8
 7 ──       $(Expr(:throw_undef_if_not, :r, false))::Any
-8 ┄─ %13 = -r@_2::Any
-9 ┄─ %14 = φ (#4 => r@_2, #8 => %13)::Any
-│    %15 = Core.isdefined(%2, :contents)::Bool
-└───       goto #11 if not %15
+8 ┄─ %9  = -r@_2::Any
+9 ┄─ %10 = φ (#4 => r@_2, #8 => %9)::Any
+└───       goto #11 if not true
 10 ─       goto #12
 11 ─       $(Expr(:throw_undef_if_not, :r, false))::Any
-12 ┄ %19 = (x0 * %14)::Any
+12 ┄ %14 = (x0 * %10)::Any
 └───       goto #13
-13 ─       return %19
+13 ─       return %14
 ) => Any
```

When calling `jl_error()` or `jl_errorf()`, we must check to see if we
are so early in the bringup process that it is dangerous to attempt to
construct a backtrace because the data structures used to provide line
information are not properly setup.

This can be easily triggered by running:

```
julia -C invalid
```

On an `i686-linux-gnu` build, this will hit the "Invalid CPU Name"
branch in `jitlayers.cpp`, which calls `jl_errorf()`.  This in turn
calls `jl_throw()`, which will eventually call `jl_DI_for_fptr` as part
of the backtrace printing process, which fails as the object maps are
not fully initialized.  See the below `gdb` stacktrace for details:

```
$ gdb -batch -ex 'r' -ex 'bt' --args ./julia -C invalid
...
fatal: error thrown and no exception handler available.
ErrorException("Invalid CPU name "invalid".")

Thread 1 "julia" received signal SIGSEGV, Segmentation fault.
0xf75bd665 in std::_Rb_tree<unsigned int, std::pair<unsigned int const, JITDebugInfoRegistry::ObjectInfo>, std::_Select1st<std::pair<unsigned int const, JITDebugInfoRegistry::ObjectInfo> >, std::greater<unsigned int>, std::allocator<std::pair<unsigned int const, JITDebugInfoRegistry::ObjectInfo> > >::lower_bound (__k=<optimized out>, this=0x248) at /usr/local/i686-linux-gnu/include/c++/9.1.0/bits/stl_tree.h:1277
1277    /usr/local/i686-linux-gnu/include/c++/9.1.0/bits/stl_tree.h: No such file or directory.
 #0  0xf75bd665 in std::_Rb_tree<unsigned int, std::pair<unsigned int const, JITDebugInfoRegistry::ObjectInfo>, std::_Select1st<std::pair<unsigned int const, JITDebugInfoRegistry::ObjectInfo> >, std::greater<unsigned int>, std::allocator<std::pair<unsigned int const, JITDebugInfoRegistry::ObjectInfo> > >::lower_bound (__k=<optimized out>, this=0x248) at /usr/local/i686-linux-gnu/include/c++/9.1.0/bits/stl_tree.h:1277
 #1  std::map<unsigned int, JITDebugInfoRegistry::ObjectInfo, std::greater<unsigned int>, std::allocator<std::pair<unsigned int const, JITDebugInfoRegistry::ObjectInfo> > >::lower_bound (__x=<optimized out>, this=0x248) at /usr/local/i686-linux-gnu/include/c++/9.1.0/bits/stl_map.h:1258
 #2  jl_DI_for_fptr (fptr=4155049385, symsize=symsize@entry=0xffffcfa8, slide=slide@entry=0xffffcfa0, Section=Section@entry=0xffffcfb8, context=context@entry=0xffffcf94) at /cache/build/default-amdci5-4/julialang/julia-master/src/debuginfo.cpp:1181
 #3  0xf75c056a in jl_getFunctionInfo_impl (frames_out=0xffffd03c, pointer=4155049385, skipC=0, noInline=0) at /cache/build/default-amdci5-4/julialang/julia-master/src/debuginfo.cpp:1210
 #4  0xf7a6ca98 in jl_print_native_codeloc (ip=4155049385) at /cache/build/default-amdci5-4/julialang/julia-master/src/stackwalk.c:636
 #5  0xf7a6cd54 in jl_print_bt_entry_codeloc (bt_entry=0xf0798018) at /cache/build/default-amdci5-4/julialang/julia-master/src/stackwalk.c:657
 #6  jlbacktrace () at /cache/build/default-amdci5-4/julialang/julia-master/src/stackwalk.c:1090
 #7  0xf7a3cd2b in ijl_no_exc_handler (e=0xf0794010) at /cache/build/default-amdci5-4/julialang/julia-master/src/task.c:605
 #8  0xf7a3d10a in throw_internal (ct=ct@entry=0xf070c010, exception=<optimized out>, exception@entry=0xf0794010) at /cache/build/default-amdci5-4/julialang/julia-master/src/task.c:638
 #9  0xf7a3d330 in ijl_throw (e=0xf0794010) at /cache/build/default-amdci5-4/julialang/julia-master/src/task.c:654
 #10 0xf7a905aa in ijl_errorf (fmt=fmt@entry=0xf7647cd4 "Invalid CPU name \"%s\".") at /cache/build/default-amdci5-4/julialang/julia-master/src/rtutils.c:77
 #11 0xf75a4b22 in (anonymous namespace)::createTargetMachine () at /cache/build/default-amdci5-4/julialang/julia-master/src/jitlayers.cpp:823
 #12 JuliaOJIT::JuliaOJIT (this=<optimized out>) at /cache/build/default-amdci5-4/julialang/julia-master/src/jitlayers.cpp:1044
 #13 0xf7531793 in jl_init_llvm () at /cache/build/default-amdci5-4/julialang/julia-master/src/codegen.cpp:8585
 #14 0xf75318a8 in jl_init_codegen_impl () at /cache/build/default-amdci5-4/julialang/julia-master/src/codegen.cpp:8648
 #15 0xf7a51a52 in jl_restore_system_image_from_stream (f=<optimized out>) at /cache/build/default-amdci5-4/julialang/julia-master/src/staticdata.c:2131
 #16 0xf7a55c03 in ijl_restore_system_image_data (buf=0xe859c1c0 <jl_system_image_data> "8'\031\003", len=125161105) at /cache/build/default-amdci5-4/julialang/julia-master/src/staticdata.c:2184
 #17 0xf7a55cf9 in jl_load_sysimg_so () at /cache/build/default-amdci5-4/julialang/julia-master/src/staticdata.c:424
 #18 ijl_restore_system_image (fname=0x80a0900 "/build/bk_download/julia-d78fdad601/lib/julia/sys.so") at /cache/build/default-amdci5-4/julialang/julia-master/src/staticdata.c:2157
 #19 0xf7a3bdfc in _finish_julia_init (rel=rel@entry=JL_IMAGE_JULIA_HOME, ct=<optimized out>, ptls=<optimized out>) at /cache/build/default-amdci5-4/julialang/julia-master/src/init.c:741
 #20 0xf7a3c8ac in julia_init (rel=<optimized out>) at /cache/build/default-amdci5-4/julialang/julia-master/src/init.c:728
 #21 0xf7a7f61d in jl_repl_entrypoint (argc=<optimized out>, argv=0xffffddf4) at /cache/build/default-amdci5-4/julialang/julia-master/src/jlapi.c:705
 #22 0x080490a7 in main (argc=3, argv=0xffffddf4) at /cache/build/default-amdci5-4/julialang/julia-master/cli/loader_exe.c:59
```

To prevent this, we simply avoid calling `jl_errorf` this early in the
process, punting the problem to a later PR that can update guard
conditions within `jl_error*`.

Before:

```julia-repl
julia> missing(1)
ERROR: MethodError: objects of type Missing are not callable.
In case you did not try calling it explicitly, check if a Missing has been passed as an argument to a method that expects a callable instead.
The object of type `Missing` exists, but no method is defined for this combination of argument types when trying to treat it as a callable object.┌ Error: Hint-handler nonsetable_type_hint_handler for MethodError in Base caused an error
│   exception =
│    1-element ExceptionStack:
│    TypeError: non-boolean (Missing) used in boolean context
│    Stacktrace:
│      [1] nonsetable_type_hint_handler(io::Any, ex::Any, arg_types::Any, kwargs::Any)
│        @ Base ./errorshow.jl:1054
│      [2] show_error_hints(::IOContext{Base.TTY}, ::MethodError, ::Vector{Any}, ::Vararg{Vector{Any}})
│        @ Base.Experimental ./experimental.jl:322
│      [3] showerror(io::IO, ex::MethodError)
│        @ Base ./errorshow.jl:374
│      [4] showerror(io::IOContext{Base.TTY}, ex::MethodError, bt::Vector{Base.StackTraces.StackFrame}; backtrace::Bool)
│        @ Base ./errorshow.jl:106
│      [5] show_exception_stack(io::IOContext{Base.TTY}, stack::Base.ExceptionStack)
│        @ Base ./errorshow.jl:1017
│      [6] display_error(io::IOContext{Base.TTY}, stack::Base.ExceptionStack)
│        @ Base ./client.jl:117
│      [7] repl_display_error(errio::IO, errval::Any)
│        @ REPL ~/.julia/juliaup/julia-nightly/share/julia/stdlib/v1.13/REPL/src/REPL.jl:565
│      [8] print_response(errio::IO, response::Any, backend::Union{Nothing, REPL.REPLBackendRef}, show_value::Bool, have_color::Bool, specialdisplay::Union{Nothing, AbstractDisplay})
│        @ REPL ~/.julia/juliaup/julia-nightly/share/julia/stdlib/v1.13/REPL/src/REPL.jl:582
│      [9] (::REPL.var"#print_response##0#print_response##1"{REPL.LineEditREPL, Pair{Any, Bool}, Bool, Bool})(io::Any)
│        @ REPL ~/.julia/juliaup/julia-nightly/share/julia/stdlib/v1.13/REPL/src/REPL.jl:556
│     [10] with_repl_linfo(f::Any, repl::REPL.LineEditREPL)
│        @ REPL ~/.julia/juliaup/julia-nightly/share/julia/stdlib/v1.13/REPL/src/REPL.jl:829
│     [11] print_response(repl::REPL.AbstractREPL, response::Any, show_value::Bool, have_color::Bool)
│        @ REPL ~/.julia/juliaup/julia-nightly/share/julia/stdlib/v1.13/REPL/src/REPL.jl:554
│     [12] (::REPL.var"#do_respond#73"{Bool, Bool, REPL.var"#setup_interface##12#setup_interface##13"{REPL.LineEditREPL, REPL.REPLHistoryProvider}, REPL.LineEditREPL, REPL.LineEdit.Prompt})(s::REPL.LineEdit.MIState, buf::Any, ok::Bool)
│        @ REPL ~/.julia/juliaup/julia-nightly/share/julia/stdlib/v1.13/REPL/src/REPL.jl:1186
│     [13] run_interface(terminal::REPL.Terminals.TextTerminal, m::REPL.LineEdit.ModalInterface, s::REPL.LineEdit.MIState)
│        @ REPL.LineEdit ~/.julia/juliaup/julia-nightly/share/julia/stdlib/v1.13/REPL/src/LineEdit.jl:2852
│     [14] run_frontend(repl::REPL.LineEditREPL, backend::REPL.REPLBackendRef)
│        @ REPL ~/.julia/juliaup/julia-nightly/share/julia/stdlib/v1.13/REPL/src/REPL.jl:1657
│     [15] (::REPL.var"JuliaLang#61#62"{REPL.LineEditREPL, REPL.REPLBackendRef})()
│        @ REPL ~/.julia/juliaup/julia-nightly/share/julia/stdlib/v1.13/REPL/src/REPL.jl:648
└ @ Base.Experimental experimental.jl:325

Stacktrace:
 [1] top-level scope
   @ REPL[1]:1
```

After:

```julia-repl
julia> missing(1)
ERROR: MethodError: objects of type Missing are not callable.
In case you did not try calling it explicitly, check if a Missing has been passed as an argument to a method that expects a callable instead.
The object of type `Missing` exists, but no method is defined for this combination of argument types when trying to treat it as a callable object.
Stacktrace:
 [1] top-level scope
   @ REPL[3]:1
```

---------

Co-authored-by: Ian Butterworth <i.r.butterworth@gmail.com>

Simplify `workqueue_for`. While not strictly necessary, the acquire load
in `getindex(once::OncePerThread{T,F}, tid::Integer)` makes
ThreadSanitizer happy. With the existing implementation, we get false
positives whenever a thread other than the one that originally allocated
the array reads it:

```
==================
WARNING: ThreadSanitizer: data race (pid=6819)
  Atomic read of size 8 at 0xffff86bec058 by main thread:
    #0 getproperty Base_compiler.jl:57 (sys.so+0x113b478)
    #1 julia_pushNOT._1925 task.jl:868 (sys.so+0x113b478)
    #2 julia_enq_work_1896 task.jl:969 (sys.so+0x5cd218)
    #3 schedule task.jl:983 (sys.so+0x892294)
    #4 macro expansion threadingconstructs.jl:522 (sys.so+0x892294)
    #5 julia_start_profile_listener_60681 Base.jl:355 (sys.so+0x892294)
    #6 julia___init___60641 Base.jl:392 (sys.so+0x1178dc)
    #7 jfptr___init___60642 <null> (sys.so+0x118134)
    #8 _jl_invoke /home/user/c/julia/src/gf.c (libjulia-internal.so.1.13+0x5e9a4)
    #9 ijl_apply_generic /home/user/c/julia/src/gf.c:3892:12 (libjulia-internal.so.1.13+0x5e9a4)
    #10 jl_apply /home/user/c/julia/src/julia.h:2343:12 (libjulia-internal.so.1.13+0xbba74)
    #11 jl_module_run_initializer /home/user/c/julia/src/toplevel.c:68:13 (libjulia-internal.so.1.13+0xbba74)
    #12 _finish_jl_init_ /home/user/c/julia/src/init.c:632:13 (libjulia-internal.so.1.13+0x9c0fc)
    #13 ijl_init_ /home/user/c/julia/src/init.c:783:5 (libjulia-internal.so.1.13+0x9bcf4)
    #14 jl_repl_entrypoint /home/user/c/julia/src/jlapi.c:1125:5 (libjulia-internal.so.1.13+0xf7ec8)
    #15 jl_load_repl /home/user/c/julia/cli/loader_lib.c:601:12 (libjulia.so.1.13+0x11934)
    #16 main /home/user/c/julia/cli/loader_exe.c:58:15 (julia+0x10dc20)

  Previous write of size 8 at 0xffff86bec058 by thread T2:
    #0 IntrusiveLinkedListSynchronized task.jl:863 (sys.so+0x78d220)
    #1 macro expansion task.jl:932 (sys.so+0x78d220)
    #2 macro expansion lock.jl:376 (sys.so+0x78d220)
    #3 julia_workqueue_for_1933 task.jl:924 (sys.so+0x78d220)
    #4 julia_wait_2048 task.jl:1204 (sys.so+0x6255ac)
    #5 julia_task_done_hook_49205 task.jl:839 (sys.so+0x128fdc0)
    #6 jfptr_task_done_hook_49206 <null> (sys.so+0x902218)
    #7 _jl_invoke /home/user/c/julia/src/gf.c (libjulia-internal.so.1.13+0x5e9a4)
    #8 ijl_apply_generic /home/user/c/julia/src/gf.c:3892:12 (libjulia-internal.so.1.13+0x5e9a4)
    #9 jl_apply /home/user/c/julia/src/julia.h:2343:12 (libjulia-internal.so.1.13+0x9c79c)
    #10 jl_finish_task /home/user/c/julia/src/task.c:345:13 (libjulia-internal.so.1.13+0x9c79c)
    #11 jl_threadfun /home/user/c/julia/src/scheduler.c:122:5 (libjulia-internal.so.1.13+0xe7db8)

  Thread T2 (tid=6824, running) created by main thread at:
    #0 pthread_create <null> (julia+0x85f88)
    #1 uv_thread_create_ex /workspace/srcdir/libuv/src/unix/thread.c:172 (libjulia-internal.so.1.13+0x1a8d70)
    #2 _finish_jl_init_ /home/user/c/julia/src/init.c:618:5 (libjulia-internal.so.1.13+0x9c010)
    #3 ijl_init_ /home/user/c/julia/src/init.c:783:5 (libjulia-internal.so.1.13+0x9bcf4)
    #4 jl_repl_entrypoint /home/user/c/julia/src/jlapi.c:1125:5 (libjulia-internal.so.1.13+0xf7ec8)
    #5 jl_load_repl /home/user/c/julia/cli/loader_lib.c:601:12 (libjulia.so.1.13+0x11934)
    #6 main /home/user/c/julia/cli/loader_exe.c:58:15 (julia+0x10dc20)

SUMMARY: ThreadSanitizer: data race Base_compiler.jl:57 in getproperty
==================
```

…#61330)

Should prevent these invalidations seen when loading CurveFit.jl on
1.13:
```julia
inserting merge!(m::DataStructures.SortedDict{K, D, Ord}, others::AbstractDict{K, D}...) where {K, D, Ord<:Ordering} @ DataStructures ~/.julia/packages/DataStructures/qUuAY/src/sorted_dict.jl:473 invalidated:
   mt_backedges: 1: signature Tuple{typeof(merge!), Any, AbstractDict} triggered MethodInstance for Base.grow_to!(::AbstractDict{K, V}, ::Base.Generator{_A, Base.Compiler.IRShow.var"JuliaLang#30#31"} where _A, ::Any) where {K, V} (0 children)
                 2: signature Tuple{typeof(merge!), Any, AbstractDict} triggered MethodInstance for Base.grow_to!(::AbstractDict{K, V}, ::Base.Generator, ::Any) where {K, V} (0 children)
                 3: signature Tuple{typeof(merge!), Any, AbstractDict} triggered MethodInstance for Base.grow_to!(::AbstractDict{K, V}, ::Base.Generator, ::Any) where {K, V} (0 children)
                 4: signature Tuple{typeof(merge!), Any, AbstractDict} triggered MethodInstance for Base.grow_to!(::AbstractDict{K, V}, ::Base.Generator{I, Base.var"#Generator##0#Generator##1"{NonlinearSolveBase.Utils.var"#norm_op##2#norm_op##3"{typeof(+)}}} where I<:(Base.Iterators.Zip{Is} where Is<:Tuple{Base.AbstractBroadcasted, Base.AbstractBroadcasted}), ::Tuple{Tuple{Any, Any}, Tuple{Any, Any}}) where {K, V} (0 children)
                 5: signature Tuple{typeof(merge!), Any, AbstractDict} triggered MethodInstance for Base.grow_to!(::AbstractDict{K, V}, ::Base.Generator{_A, F} where {_A, F<:DifferentiationInterface.var"#_prepare_jacobian_aux##0#_prepare_jacobian_aux##1"}, ::Any) where {K, V} (0 children)
                 6: signature Tuple{typeof(merge!), Any, AbstractDict} triggered MethodInstance for Base.grow_to!(::AbstractDict{K, V}, ::Base.Generator{_A, F} where {_A, F<:DifferentiationInterface.var"#_prepare_jacobian_aux##12#_prepare_jacobian_aux##13"}, ::Any) where {K, V} (0 children)
                 7: signature Tuple{typeof(merge!), Any, AbstractDict} triggered MethodInstance for Base.grow_to!(::AbstractDict{K, V}, ::Base.Generator{I, Base.var"#Generator##0#Generator##1"{NonlinearSolveBase.Utils.var"#norm_op##2#norm_op##3"{typeof(+)}}} where I<:(Base.Iterators.Zip{Is} where Is<:Tuple{Base.AbstractBroadcasted, Vector{Float64}}), ::Tuple{Tuple{Any, Any}, Int64}) where {K, V} (0 children)
   backedges: 1: superseding merge!(d::AbstractDict, others::AbstractDict...) @ Base abstractdict.jl:224 with MethodInstance for merge!(::AbstractDict, ::AbstractDict) (1126 children)

inserting merge(d::OrderedCollections.OrderedDict, others::AbstractDict...) @ OrderedCollections ~/.julia/dev/OrderedCollections/src/ordered_dict.jl:488 invalidated:
   mt_backedges: <38 invalidations I deleted because they have enormous types>
   backedges: 1: superseding merge(d::AbstractDict, others::AbstractDict...) @ Base abstractdict.jl:359 with MethodInstance for merge(::AbstractDict, ::Base.Pairs{Symbol, Union{}, Nothing, @NamedTuple{}}) (21 children)
              2: superseding merge(d::AbstractDict, others::AbstractDict...) @ Base abstractdict.jl:359 with MethodInstance for merge(::AbstractDict, ::Base.Pairs{Symbol, _A, Nothing, A} where {_A, A<:NamedTuple}) (2489 children)
```

Partial alternative to JuliaLang#61329. I added `mergewith()` and `mergewith!()`
to be on the safe side.