llvm supports both win32 native threads and pthread,
but configure tries to find pthread first.
This manually disables pthread to use native api.
This removes libpthreads-2.dll dependency on librustc.
The main one removed is rust_upcall_reset_stack_limit (continuation of #10156),
and this also removes the upcall_trace function. The was hidden behind a
`-Z trace` flag, but if you attempt to use this now you'll get a linker error
because there is no implementation of the 'upcall_trace' function. Due to this
no longer working, I decided to remove it entirely from the compiler (I'm also a
little unsure on what it did in the first place).
LLVM's JIT has been updated numerous times, and we haven't been tracking it at
all. The existing LLVM glue code no longer compiles, and the JIT isn't used for
anything currently.
This also rebases out the FixedStackSegment support which we have added to LLVM.
None of this is still in use by the compiler, and there's no need to keep this
functionality around inside of LLVM.
This is needed to unblock #10708 (where we're tripping an LLVM assertion).
* This has one workaround patch (everything's testing just fine...)
* I reworked the fixedstacksegment attribute to be specified with a string
rather than using a keyword and an integer and modifying the parser
* I added a "no-split-stack" attribute along the same lines as the
"fixedstacksegment" attribute for #1226
