message: Exclude third-party code from being format-checked.
  These, we'd like to keep as-is as much as possible.
diff: FORMAT_OUT=${TMPDIR:-/tmp}/clang-format-diff.out
  # Run on all files.
  -find . -name "*.h" -o -name "*.cc" | xargs -P2 clang-format -i
  +find . -name "*.h" -o -name "*.cc" | grep -v third_party/|external_libs/ \
  + | xargs -P2 clang-format -i
  # Check if we got any diff
  git diff > ${FORMAT_OUT}
  