[llvm] [dsymutil][DWARFLinker] Refactor handling mergeable libraries. (PR #80615)

[Alpha Abdoulaye via llvm-commits]

Alpha-10000 wrote:

I did not see this pR, sorry for the delayed response.
Generally looks good to me!
I verified that the attached  [relink.tar.gz](https://github.com/llvm/llvm-project/files/14674300/relink.tar.gz) produces a debuggable executable.
(`make mrproper && make all-relink && make strip && lldb`)

A few minor outstanding things:
-The tests need to be updated to reflect the changes, to at the very list stop referencing relocation maps.
- Similarly to https://github.com/llvm/llvm-project/pull/78794, could you please further update `switchToNewLibDebugMapObject` so that `addCommonSymbols/resetParserState`  is at the beginning of the function and that duplicate N_LIB entry names are tracked? To void time spent handling errors and emitting warnings.



https://github.com/llvm/llvm-project/pull/80615