[llvm] [win][aarch64] Add support for detecting the Host CPU on Arm64 Windows (PR #151596)

[David Green via llvm-commits]

https://github.com/davemgreen commented:

Thanks - I'm not an expert on the windows APIs side of this, but it looks good to me comparing to an X86 machine I have.

https://github.com/llvm/llvm-project/pull/151596