[clang] [clang] Add `intrin0.h` header to mimic `intrin0.h` used by MSVC STL for clang-cl (PR #75711)

[Nico Weber via cfe-commits]

nico wrote:

Wow, that clang/lib/Headers/yvals_core.h hacks is gross, I love it :D

lgtm, and good to land provided you do a quick re-check to confirm that this doesn't tank compile times now with that part included. Thanks!

https://github.com/llvm/llvm-project/pull/75711