[llvm] [llvm-debuginfo-analyzer] Apply various memory savings in Core/LVxxx base classes (PR #144399)

[Javier Lopez-Gomez via llvm-commits]

jalopezg-git wrote:

I have also made a couple of (very trivial) changes to `LVScopeCompileUnit` definition leading to some additional memory savings.

@CarlosAlbertoEnciso, @OCHyams, if you don't have further comments, I think this can be merged too :+1:.

https://github.com/llvm/llvm-project/pull/144399