BUG: Additional fix necessary for issue #8481 so that Xcode builds do not write files into the source tree. Also add a test that runs last to check for local modifications in CMake_SOURCE_DIR based on whether 'cvs -q -n up -dP' output is empty. Test fails on dashboard runs when there are local modifications. Test passes on non-dashboard runs with local modifications so that CMake developers may have mods when running the test locally.