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

[Daniel Rodríguez Troitiño via llvm-commits]

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drodriguez wrote:

If it needs to be exactly 64 bits, maybe add a `static_assert`? Also not sure about the endianness (is it constant endianess, depends on the host or the target machine?)

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