Fix application shutdown with XPlane HIL

src/comm/QGCXPlaneLink.cc

@@ -267,8 +267,6 @@ void QGCXPlaneLink::run()
 
     emit simulationDisconnected();
     emit simulationConnected(false);
-
-    this->deleteLater();
 }
 
 void QGCXPlaneLink::setPort(int localPort)

src/uas/UAS.cc

@@ -243,6 +243,8 @@ UAS::UAS(MAVLinkProtocol* protocol, int id) : UASInterface(),
 UAS::~UAS()
 {
     stopHil();
+    // wait for the simulator to exit
+    simulation->wait();
     simulation->deleteLater();
     writeSettings();
 }