message: build_system: fix make clean so that it deteles all builds except build/third_party
diff: @@ -152,7 +152,7 @@ distclean:
  @rm -rf logs/
  clean:
  - @if [ -d build ]; then find build -mindepth 2 -delete -path "build/*/third_party"; fi
  + @if [ -d build ]; then find build -mindepth 2 ! -regex 'build/\w+/third_party.*' -delete; fi
  android_env_check:
  ifndef ANDROID_TOOLCHAIN_CMAKE
  