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

[Fangrui Song via cfe-commits]

MaskRay wrote:

I am not familiar with the MSVC ecosystem, but the change looks reasonable. Thanks!

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