oops! I cherry-picked rL374820 thinking it was completely
independent of D68737, but it wasn't. It makes an incidental
use of SBFile::GetFile, which is introduced there, so I broke the
build.
The docs say you can commit without review for "obvious". I think
this qualifies. If this kind of fix isn't considered obvious, let
me know and I'll revert instead.
Fixes: rL374820
llvm-svn: 374825