In the debug runtime, caml_prim_name_table remains for the lifetime of
the program, as it's used by instrtrace.c, but in normal operation, once
the list of primitives has been handed over to Dynlink, it's no longer
required. In the normal runtime, it's now freed after this handover.

In passing, strings themselves are no longer duplicated, as the code
path is a good deal simpler than it used to be, and the bytecode section
itself can reliably be used as the underlying buffer for
caml_prim_name_table.

caml_shared_libs_path is only kept at all to be handed over to Dynlink.
It, along with the two underlying buffers for CAML_LD_LIBRARY_PATH and
ld.conf are freed after the call.