[lld] [lld][AArch64][ELF][PAC] Support `.relr.auth.dyn` section (PR #96496)

[via llvm-commits]

zeroomega wrote:

I confirm it no longer generate empty `.rel.dyn` or invalid sh_info on REL section when building an relocatable object file.

https://github.com/llvm/llvm-project/pull/96496