disbale exit-button as long as update process is running

worker.cpp

@@ -122,6 +122,7 @@ void Worker::privateUpdate() {
     start->setEnabled(false);
 
     emit stopStartTimer();
+    emit disableExit();
     m_updateProcessRunning = true;
 
     bool sentIsmasLastVersionNotification = false;
@@ -217,6 +218,7 @@ void Worker::privateUpdate() {
     }
 
     m_updateProcessRunning = false;
+    emit enableExit();
     emit restartExitTimer();
 }