PR21195: Emit .gcno files to the proper location.

When building with coverage, -no-integrated-as, and -c, the driver was
emitting -cc1 -coverage-file pointing at a file in /tmp. Ensure the
coverage file is emitted in the same directory as the output file.


git-svn-id: http://llvm.org/svn/llvm-project/cfe/trunk@219460 91177308-0d34-0410-b5e6-96231b3b80d8