line info test failure after commit 173592

[Eli Bendersky]

>> Did you look at this failure? I attached the tmp file again.
>
> Sorry, I believe the general idea is that llvm-dwarfdump doesn't
> support COFF relocations. You/we/someone could add them and/or we
> could make this test case target-specific so it doesn't get muddled up
> by COFF until someone does that.
>

I didn't know we even emit DWARF into COFF - do we? I know mingw does
that, but it's because mingw's gdb knows how to handle it.

Eli