[clang] [PAC][clang] Add new features to pauthtest ABI (PR #113150)

[Fangrui Song via cfe-commits]

MaskRay wrote:

Sorry, I haven't closely followed the AArch64 PAuth work. The Clang driver options should come last in the patch stack, with other patches reviewed first.

For driver options, I don't know a bunch of `-fptrauth-*` is a good idea. We had a similar scenario with -mbranches-within-32B-boundaries (an umbrella option): the individual options are essentially never used. Have you thought about `-fptrauth-something=call,return,indirect-goto`?

https://github.com/llvm/llvm-project/pull/113150