[llvm] [AArch64] Fix return address auth in swiftasync epilogues (PR #189484)

[Oliver Hunt via llvm-commits]

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ojhunt wrote:

Does this impact non-swiftcc codegen at all? (basically "is it worth adding non-swift behavior tests as well?")

Also title does seem to indicate swiftasync right now, was that just updated for clarity?

https://github.com/llvm/llvm-project/pull/189484