[lld] [llvm] [lld][MachO] Add ARM64e pointer authentication linking support (PR #188378)

[Ellis Hoag via llvm-commits]

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ellishg wrote:

```suggestion
        uint64_t segmentBase = referentIsec->parent->parent->addr;
        writeChainedRebase(loc, referentVA, segmentBase, r.getAuthInfo());
```
If we make `getAuthInfo()` return a pointer then that will simplify a lot here.

https://github.com/llvm/llvm-project/pull/188378