[lld] [lld][ELF] Support LLVM repository and LLVM revision information (PR #97323)

[Fangrui Song via llvm-commits]

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

LGTM. The `After this change:` part in the description should be adjusted.
The output is probably for LLVM_APPEND_VC_REV=on

https://github.com/llvm/llvm-project/pull/97323