[llvm] [BOLT][AArch64] Handle OpNegateRAState to enable optimizing binaries with pac-ret hardening (PR #120064)

[Gergely Bálint via llvm-commits]

bgergely0 wrote:

Force push: an implementation of `getSignedReg` has been merged into main, so my previous rebase had both with a slightly different signature.

https://github.com/llvm/llvm-project/pull/120064