CI: better checking of formatting

.drone.yml

@@ -28,7 +28,4 @@ steps:
   image: cppbuilder:v0.4
   commands:
   - cd mario
-  - FORMAT="ok"
-  - while read f ; do clang-format -style=file "$f" > temp.pp ; if [ $(diff temp.pp "$f" | wc -l) -gt 0 ] ; then echo "$f needs reformatting" ; FORMAT="nok" ; fi ; done <<< "$(find . -iname '*pp')"
-  - rm temp.pp
-  - if [ "$FORMAT" == "nok" ] ; then exit 1 ; fi
+  - find .  -path "./build" -prune -or \( -iname "*.cpp" -or -iname "*.hpp" \) | xargs -P0 -I{} clang-format -style=file --dry-run -Werror {}