[llvm] [llvm][dsymutil] Use the DW_AT_name of the uniqued DIE for insertion into .debug_names (PR #168513)

[David Blaikie via llvm-commits]

dwblaikie wrote:

Yeah, mixed feelings - as I've said elsewhere, there are lots of ways one could end up with equivalent-but-not-identical names in DWARF, and so supporting those correctly in dsymutil seems nice (especially if you expect to/likely will support inputs from different compilers, or at least different compiler versions - we wouldn't want an improvement to clang pretty name printing to break dsymutil). 

But, similarly, clang should generate names that agree with itself and are exactly as unique as the linkage and isn't in this case.

https://github.com/llvm/llvm-project/pull/168513