[clang] [llvm] Reland "[DebugMetadata][DwarfDebug] Support function-local types in lexical block scopes (4/7)" (PR #165032)

[Jeremy Morse via cfe-commits]

https://github.com/jmorse approved this pull request.

Thanks for sticking with this; github has done its favourite thing of chucking away half the comments, so it's a bit difficult to re-review. Looking at what I wrote last time, I think everything's been addressed, I would only add that you could put the explanation of the MetadataLoader.cpp `upgradeCULocals` function into a comment there for future reference.

This LGTM, modulo Davids comments.

https://github.com/llvm/llvm-project/pull/165032