[lld] [ELF] Improve undefined symbol message w/ DW_TAG_variable but w/o line number information (PR #70854)

[Bevin Hansson via llvm-commits]

https://github.com/bevin-hansson approved this pull request.

LGTM, it accomplishes the same thing as the original PR I submitted.

https://github.com/llvm/llvm-project/pull/70854