[openmp] Silence warning when compiling with MSVC targetting x86

This fixes:
```
[3593/7449] Building CXX object projects\openmp\runtime\src\CMakeFiles\omp.dir\kmp_debug.cpp.obj
C:\git\llvm-project\openmp\runtime\src\kmp_os.h(471): warning C4163: '_InlineInterlockedExchange64': not available as an intrinsic function
```
GitOrigin-RevId: ca0e2417912d8dea49c053186402aafe1ac8995a
1 file changed