Revert "[Tooling] Parse compilation database command lines on Windows."

This reverts commit 27a874790fc79f6391ad3703d7c790f51ac6ae1f.

After the introduction of windows command line parsing, some unit tests
began failing that expect to test gnu style command line quirks.  The
fix is mechanical but time consuming, so revert this for now.

llvm-svn: 278976