[llvm] [BOLT] Gadget scanner: factor out utility code (PR #131895)

[Anatoly Trosinenko via llvm-commits]

atrosinenko wrote:

Added a basic test for debug output - this looks like a useful overview for what gadget scanner does. This helped identify a few issues with debug output in the next patches.

https://github.com/llvm/llvm-project/pull/131895