message: config: Fix for StringOutputStream memory safety.
  StringOutputStream needs to be destroyed before its associated string is
  accessed (See
  https://developers.google.com/protocol-buffers/docs/reference/cpp/google.protobuf.io.zero_copy_stream_impl_lite#StringOutputStream.StringOutputStream.details).
diff: @@ -53,10 +53,14 @@ public:
  // Use Protobuf::io::CodedOutputStream to force deterministic serialization, so that the same
  // message doesn't hash to different values.
  ProtobufTypes::String text;
  + {
  + // For memory safety, the StringOutputStream needs to be destroyed before
  + // we read the string.
  Protobuf::io::StringOutputStream string_stream(&text);
  Protobuf::io::CodedOutputStream coded_stream(&string_stream);
  coded_stream.SetSerializationDeterministic(true);
  message.SerializeToCodedStream(&coded_stream);
  + }
  return std::hash<std::string>{}(text);
  }
  