Fixes PR17018. Only partial test coverage because I don't want
to try to write a test which generates a file whose name contains a newline.
llvm-svn: 189557
- This diverges from gcc, and confuses tools (like dtrace) which track # line
markers as a way to determine which content is in the context of the main
file.
llvm-svn: 168128
Eli Friedman