message: threaded_queue.hh: fix -Wpessimizing-move
diff: @@ -135,7 +135,7 @@ public:
  auto val = std::move(q->front());
  q->pop_front();
  --total_count_;
  - return std::move(val);
  + return val;
  };
  if (!priority_.empty())
  return execute(&priority_);
  @@ -150,7 +150,7 @@ public:
  auto val = std::move(q->front());
  q->pop_front();
  --total_count_;
  - return std::move(val);
  + return val;
  };
  if (priority_.size())
  return execute(&priority_);
  