[llvm] [BOLT] Change Relocation Type to 32-bit and add Optional flag (PR #130792)

[Maksim Panchenko via llvm-commits]

https://github.com/maksfb commented:

Thanks! Looks good, but please change the struct layout. Better yet, introduce `Optional` in a new PR where it's being used.

https://github.com/llvm/llvm-project/pull/130792