[PAC][ibunwind] Support signed personality pointer on Linux targets

[kovdan01]

Linux and Apple targets have different ways of signing personality function pointer (particularly, different discriminator is used). See #119361 for Linux implementation on llvm side.

#143230 introduces handling of signed personality function pointer, but only for Apple targets. We should support this on Linux targets as well.

Proposed fix (initially suggested by @atrosinenko): e2f8b9d

[kovdan01]

Tagging @asl @ojhunt @atrosinenko

[ojhunt]

I think I've already included this in the main PR now

[kovdan01]

I think I've already included this in the main PR now

@ojhunt Thanks! I've ensured that your recent changes include a fix for this.

Closing the issue as it's no longer relevant.