[llvm] [DWARF] Emit a minimal line-table for totally empty functions (PR #107267)

[Chen Zheng via llvm-commits]

https://github.com/chenzheng1030 approved this pull request.

The change to XCOFF case and the debug line table LGTM. Better to wait for another look : )

https://github.com/llvm/llvm-project/pull/107267