iOS: Send application state changes synchronously

The user might have a limited time to react when the application is
suspended, so we need to send the event as soon as possible.

Change-Id: Ib6c342f5426cf15e36ba4ef57edf30878f86d1c9
Reviewed-by: Richard Moe Gustavsen <richard.gustavsen@digia.com>

src/plugins/platforms/ios/qiosapplicationstate.mm

@@ -150,6 +150,7 @@
         break;
     }
     QWindowSystemInterface::handleApplicationStateChanged(state);
+    QWindowSystemInterface::flushWindowSystemEvents();
 }
 
 @end