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

[Daniil Kovalev via llvm-commits]

kovdan01 wrote:

> I think we should suppress the creation of `.rela.dyn` in the first place.
> I will try updating `createSyntheticSections`.

@MaskRay I agree that it's better not to construct the section at all if we know it's not needed than construct an empty one and then delete it, thanks for implementing that it ebc123e0793a1cbcb69b4af1548e339e018ffff2.

> The `!config->relocatable` condition in `removeUnusedSyntheticSections` in this PR can then be dropped.

Deleted, thanks. I also updated the PR description.

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