[libunwind] [libunwind][AArch64] Protect PC within libunwind's context. (PR #113368)

[Oliver Hunt via cfe-commits]

ojhunt wrote:

Sorry, I missed this

Now that the ptrauth qualifier is available I'm going to be preparing and pushing the darwin libunwind+personality function changes, which are very aggressive in there protection of data and pointers

https://github.com/llvm/llvm-project/pull/113368