CMake: only run the ClangFormat test if we have version 11+ of ClangFormat.
CMake: only run the ClangFormat test if we have version 11+ of ClangFormat.


hsorby/libcellml,cellml/libcellml,nickerso/libcellml,hsorby/libcellml,nickerso/libcellml,cellml/libcellml,hsorby/libcellml,nickerso/libcellml,cellml/libcellml,hsorby/libcellml,cellml/libcellml,nickerso/libcellml