IIUC, this is a .clang-format that can be (but is not required to be) used to format source code and prevent comments about formatting.
At this point, we are not enforcing a shift to clang-format as the code standard for LilyPond. If this is true, LGTM. If we are enforcing a shift to clang-format, then I think we need an LGTM from David K. https://codereview.appspot.com/561340043/
