[clang] [PAC] Add support for __ptrauth type qualifier (PR #100830)

[Akira Hatanaka via cfe-commits]

ahatanak wrote:

Any other feedback on this patch?

For those who haven't followed the RFC, the RFC received positive reviews, and we have reached a consensus to move forward with the proposal. https://discourse.llvm.org/t/rfc-ptrauth-qualifier/80710/31

https://github.com/llvm/llvm-project/pull/100830