[llvm] [PAC][AArch64] Lower ptrauth constants in code (PR #94241)

[Thorsten Schütt via llvm-commits]

tschuett wrote:

You added a new GlobalIsel named opcode. You may want to check it's invariants in the MachineVerifier:
https://github.com/llvm/llvm-project/blob/main/llvm/lib/CodeGen/MachineVerifier.cpp

https://github.com/llvm/llvm-project/pull/94241