coding-style-check: Skip if clang-format not found (#23)

cmake/check-coding-style.sh

@@ -18,6 +18,7 @@ if which clang-format-14 > /dev/null; then
     echo "Code formatting incorrect!"
   fi
 else
+  echo 77 > "${ERRFILE}"
   echo "WARNING: clang-format-14 not found, code formatting not checked!"
 fi
 

cmake/enable_code_style_check.cmake

@@ -20,3 +20,6 @@
 enable_testing()
 add_test(NAME coding_style COMMAND ${CMAKE_SOURCE_DIR}/cmake/check-coding-style.sh ${CMAKE_BINARY_DIR}
                            WORKING_DIRECTORY ${CMAKE_SOURCE_DIR})
+
+# coding style will return 77 if no clang-format-14 could be found AND none of the other tests fail
+set_property(TEST coding_style PROPERTY SKIP_RETURN_CODE 77)