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

[Daniil Kovalev via llvm-commits]

kovdan01 wrote:

> To the best of my knowledge I'm not aware of any of these as this is the only serious implementation of the ELF spec.

I'm not aware of such implementations as well.

I suppose we can do the following:
- Update the spec and remove PT_NOTE from it. If someone needs it for some reason, they can ask for it explicitly.
- Keep only GNU property support in lld.

@MaskRay @smithp35 Please let me know what do you think on this. I'll update the PR depending on your answers.

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