[llvm] [DWARF5][COFF] Fix wrong relocation in .debug_line (PR #83773)

[David Blaikie via llvm-commits]

dwblaikie wrote:

I don't know enough about the COFF side of DWARF (maybe @zmodem would have some pointers to folks more versed in this) - but as for a test case. I'd expect some sort of objdump tool on the resulting COFF Object and observing the different kind of relocation would be suitable.

(if I were reviewing this in more detail (other reviewers might already be familiar with the context and not need this explained) I'd want to know more/understand why the old code is still in a fallback path/how the code is valid in that case & what that case (`needsDwarfSectionOffsetDirective`) is)

https://github.com/llvm/llvm-project/pull/83773