[lld] [lld][ELF] Add --debug-names to create merged .debug_names. (PR #86508)

[via llvm-commits]

cmtice wrote:

@clayborg Yes, the idea is that there will be a single merged .debug_names index in the final binary that combines (merges) all the .debug_names indices from all the .o files.  As @ayermolo has indicated, the plan is that all .debug_name entries with a DW_IDX_type_unit attribute will also contain a DW_IDX_compile_unit attribute. I think that should solve the problem you were concerned about? Or am I missing something?

https://github.com/llvm/llvm-project/pull/86508