[llvm] [BOLT][binary-analysis] Fix pac-ret scanner's "major limitation" (PR #136664)

[Gergely Bálint via llvm-commits]

bgergely0 wrote:

Looks like many binaries have `paciasp`/`autiasp` + the `.cfi_negate_ra_state` in `__do_global_dtors_aux`.
These small unittest targets do not run into `unwindCFIState` and similar functions where `unsupported CFI opcode` would be triggered. Problem is, the `__do_global_dtors_aux` is coming from a precompiled object on the system (as I currently understand it), so the user does not control the flags it is compiled with.

https://github.com/llvm/llvm-project/pull/136664