message: Fixed sorting assertion with some std::sort implementations.
  Tested: on Linux.
diff: @@ -912,7 +912,9 @@ class Builder FLATBUFFERS_FINAL_CLASS {
  auto comp = strcmp(as, bs);
  // If this assertion hits, you've added two keys with the same value to
  // this map.
  - assert(comp);
  + // TODO: Have to check for pointer equality, as some sort implementation
  + // apparently call this function with the same element?? Why?
  + assert(comp || &a == &b);
  return comp < 0;
  });
  // First create a vector out of all keys.
  