proper spinning loop

src/comm/QGCXPlaneLink.cc

@@ -144,7 +144,9 @@ void QGCXPlaneLink::setVersion(unsigned int version)
  **/
 void QGCXPlaneLink::run()
 {
-    exec();
+    forever {
+        QGC::SLEEP::usleep(500000);
+    }
 }
 
 void QGCXPlaneLink::setPort(int localPort)

src/comm/UDPLink.cc

@@ -69,7 +69,9 @@ UDPLink::~UDPLink()
  **/
 void UDPLink::run()
 {
-	exec();
+    forever {
+        QGC::SLEEP::usleep(500000);
+    }
 }
 
 void UDPLink::setAddress(QHostAddress host)