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

[Daniel Rodríguez Troitiño via llvm-commits]

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drodriguez wrote:

It is not very expensive, but it is also not very cheap either. The function is invoked for every `writeChainedRebase`, `writeChainedBind` and every chained section `writeTo`. Maybe it should be calculated once and saved, and then passed into `writeChainedRebase`, `writeChainedBind` and others from `writeTo`.

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