Don't hold a mission flight status copy

src/MissionManager/VisualMissionItem.cc

@@ -152,12 +152,11 @@ void VisualMissionItem::setAzimuth(double azimuth)
 
 void VisualMissionItem::setMissionFlightStatus(MissionController::MissionFlightStatus_t& missionFlightStatus)
 {
-    _missionFlightStatus = missionFlightStatus;
+    if (qIsNaN(missionFlightStatus.gimbalYaw) && qIsNaN(_missionGimbalYaw)) {
-    if (qIsNaN(_missionFlightStatus.gimbalYaw) && qIsNaN(_missionGimbalYaw)) {
         return;
     }
-    if (!qFuzzyCompare(_missionFlightStatus.gimbalYaw, _missionGimbalYaw)) {
+    if (!qFuzzyCompare(missionFlightStatus.gimbalYaw, _missionGimbalYaw)) {
-        _missionGimbalYaw = _missionFlightStatus.gimbalYaw;
+        _missionGimbalYaw = missionFlightStatus.gimbalYaw;
         emit missionGimbalYawChanged(_missionGimbalYaw);
     }
 }

src/MissionManager/VisualMissionItem.h

@@ -271,8 +271,6 @@ protected:
     VisualMissionItem*      _parentItem =               nullptr;
     QGCGeoBoundingCube      _boundingCube;                          ///< The bounding "cube" of this element.
 
-    MissionController::MissionFlightStatus_t    _missionFlightStatus;
-
     /// This is used to reference any subsequent mission items which do not specify a coordinate.
     QmlObjectListModel  _childItems;