[llvm] [PAC][InstCombine] Replace auth+sign with resign (PR #130807)

[Nikita Popov via llvm-commits]

https://github.com/nikic commented:

Looks fine from InstCombine perspective. One thing you might want to consider/test is what should happen if the ptrauth.auth has another use. Do you want to replace the sign with resign in that case, given that the auth will stay around?

https://github.com/llvm/llvm-project/pull/130807