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

[Ellis Hoag via llvm-commits]

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ellishg wrote:

```suggestion
static_assert(sizeof(AuthReloc) == sizeof(int64_t), "AuthReloc must match int64_t size");
```

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