[clang] [llvm] [X86] Enhance kCFI type IDs with a 3-bit arity indicator. (PR #117121)

[Fangrui Song via cfe-commits]

MaskRay wrote:

If you are changing the hash scheme, please migrate from xxHash64 to xxh3. We want to remove the legacy xxHash64 from LLVM.

https://github.com/llvm/llvm-project/pull/117121