This allows to run the contents of a buffer through "rust run" and show
the results in a scratch buffer. Handy for things that are just a bit
too big to be done comfortably in rusti.

Refs rust-lang#7747

Note that this is not actually *used* by default; it is a matter of
configuration still, because you might want to:

- Compile all .rs files with `rustc %` (where each can be built itself)

- Compile all .rs files with `rustc some-file.rs` (where you are editing
  part of a crate)

- Compile with a different tool, such as `make`. (In this case you might
  put a `~/.vim/after/compiler/rustc.vim` to match such cases, set
  makeprg and extend errorformat as appropriate. That should probably go
  in a different compiler mode, e.g. make-rustc.)

To try using it, `:compiler rustc`. Then, `:make` on a file you would
run `rustc` on will work its magic, invoking rustc. To automate this,
you could have something like `autocmd FileType rust compiler rustc` in
your Vim config.

…ednet

Correctly handle signs in exponents in numeric_literal::format()

Fixes rust-lang#7744

changelog: Correctly handle signs in exponents in `numeric_literal::format()`

feat: Package Windows release artifacts as ZIP and add symbols file

Closes rust-lang#13872
Closes rust-lang#7747
CC rust-lang#10371

This allows us to ship a format that's easier to handle on Windows. As a bonus, we can also include the PDB, to get useful stack traces. Unfortunately, it adds a couple of dependencies to `xtask`, increasing the debug build times from 1.28 to 1.58 s (release from 1.60s to 2.20s) on my system.