[lld] [lld][AArch64][ELF][PAC] Support AUTH relocations and AUTH ELF marking (PR #72714)

[Fangrui Song via llvm-commits]

MaskRay wrote:

I simplified the code a bit.

I think -no-pie must use a dynamic relocation as well. See https://github.com/MaskRay/llvm-project/tree/pauth-lld-nopie

https://github.com/llvm/llvm-project/pull/72714