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

[Aaron Ballman via cfe-commits]

AaronBallman wrote:

> @AaronBallman Can you merge this please? We are eagerly waiting for this to end up in a release! ;-)

Thank you for the ping, this fell off my radar!

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