Copy recorder QoS profile to local variable so that temporary value i…

…sn't cleared (ros2#803)

Signed-off-by: Emerson Knapp <eknapp@amazon.com>

rosbag2_transport/src/rosbag2_transport/recorder.cpp

@@ -280,7 +280,8 @@ void Recorder::warn_if_new_qos_for_subscribed_topic(const std::string & topic_na
     // Already warned about this topic
     return;
   }
-  const auto & used_profile = existing_subscription->second->get_actual_qos().get_rmw_qos_profile();
+  const auto actual_qos = existing_subscription->second->get_actual_qos();
+  const auto & used_profile = actual_qos.get_rmw_qos_profile();
   auto publishers_info = this->get_publishers_info_by_topic(topic_name);
   for (const auto & info : publishers_info) {
     auto new_profile = info.qos_profile().get_rmw_qos_profile();