[clang] [AArch64][PAC][clang][ELF] Support PAuth ABI core info (PR #85235)

[Fangrui Song via cfe-commits]

https://github.com/MaskRay approved this pull request.

This will need a rebase (or merge main) as `-S -emit-llvm` tests have errors.

https://github.com/llvm/llvm-project/pull/85235