[compiler-rt] [libcxx] [libcxxabi] [libunwind] [runtimes][PAC] Harden unwinding when possible (PR #143230)

[Oliver Hunt via llvm-commits]

ojhunt wrote:

hmmm, I thought `ptrauth_calls` was one of the checks guarded by a darwin target so I might revert the `|| defined(__PTRAUTH__)` changes

https://github.com/llvm/llvm-project/pull/143230