[clang] [PAC][Driver] Support ptrauth flags only on ARM64 Darwin or with pauthtest ABI (PR #113152)

[Daniil Kovalev via cfe-commits]

kovdan01 wrote:

The rebase history was cluttered due to this being part of stack of PRs, so I've just force-pushed the correct rebased version of the changes as a single commit.

Since this is the last PR in the stack and it's already approved, I hope that missing updates history is not a critical issue, but it allows to keep things simpler.

https://github.com/llvm/llvm-project/pull/113152