message: deps: Copy protobuf internal headers needed for transcoding
  for
diff: @@ -10,3 +10,10 @@ rsync -av protobuf-$VERSION/* $THIRDPARTY_SRC/protobuf
  cd protobuf-$VERSION
  ./configure --prefix=$THIRDPARTY_BUILD --enable-shared=no
  make V=1 install
  +
  +# These internal headers are needed by the GRPC-JSON transcoding library.
  +# https://github.com/grpc-ecosystem/grpc-httpjson-transcoding
  +# TODO(htuch): Clean up protobuf deps builds with envoy-api
  +rsync -av src/google/protobuf/util/internal/*.h $THIRDPARTY_BUILD/include/google/protobuf/util/internal
  +cp src/google/protobuf/stubs/strutil.h $THIRDPARTY_BUILD/include/google/protobuf/stubs/
  +cp src/google/protobuf/stubs/statusor.h $THIRDPARTY_BUILD/include/google/protobuf/stubs/
  