[clang] [X86] Fix the implementation of __readcr[4, 8]/__writecr[4, 8] to work in 64-bit mode (PR #122238)

[Reid Kleckner via cfe-commits]

https://github.com/rnk commented:

Thanks!

I see we don't actually implement these intrinsics at this point, but fixing them to avoid redeclaration errors is reasonable.

https://github.com/llvm/llvm-project/pull/122238