[llvm] [BOLT][BTI] Refactor: move applyBTIFixup under MCPlusBuilder (PR #177164)

[Paschalis Mpeis via llvm-commits]

https://github.com/paschalis-mpeis commented:

Hey Gergely,

Had a quick pass over the change. The refactoring looks quite neat.
Does this mean we can now support hugify with BTI enabled?

That's up to you, but you could also split the hugify/patch-entry support into separate patches, outside of this refactoring.

https://github.com/llvm/llvm-project/pull/177164