[llvm] [BOLT] Gadget scanner: detect non-protected indirect calls (PR #131899)

[Jacob Bramley via llvm-commits]

https://github.com/jacobbramley commented:

What happens if `-fno-plt` is used? It appears to have no effect on AArch64 Clang, but GCC supports it, and it generates an inline GOT load followed by an indirect branch:

```
adrp  x16, ...
ldr   x16, [x16, ...]
br    x16
```

That's actually fine as long as the GOT is RELRO, but I don't think this scanner could distinguish it.

https://github.com/llvm/llvm-project/pull/131899