[llvm] [AArch64] Handle inttoptr+add+ptrtoint pattern in lowerConstantPtrAuth (PR #189474)

[Eli Friedman via llvm-commits]

https://github.com/efriedma-quic approved this pull request.

LGTM, but wait a bit to see if the ptrauth reviewers have additional comments.

https://github.com/llvm/llvm-project/pull/189474