Add style check build step.

.drone.yml

@@ -34,6 +34,11 @@ steps:
       - cmake --build build-release --target all -- -j 4
       - build-release/bin/CreatureLibTests -s --durations yes --use-colour yes
       - valgrind --tool=memcheck --gen-suppressions=all --leak-check=full --leak-resolution=med --track-origins=yes --vgdb=no --error-exitcode=1 build-release/bin/CreatureLibTests
+  - name: style-check
+    image: deukhoofd/linux64builder
+    failure: ignore
+    commands:
+      - run-clang-format.py -r src/ CInterface/ tests/
   - name: test-release-windows
     image: deukhoofd/windowsbuilder
     volumes: