[llvm] [MC] Fix DWARF file table for files with empty DWARF (#119020) (PR #119229)

[David Blaikie via llvm-commits]

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

I'm fine with this change as-is. The Masm discussion can continue/be addressed in a separate change if needed.

https://github.com/llvm/llvm-project/pull/119229