Silence warning in QtNetwork build

qnetworkconfigmanager.cpp:63:9: error: unused variable ‘shutdown’ [-Werror=unused-variable]

This warning was introduced by f273d6fbc0

Change-Id: Ied650a4d94d18495684a8f08ab5f2cd628026fb7
Reviewed-by: Jonas Gastal <gastal@intel.com>
Reviewed-by: Peter Hartmann <phartmann@blackberry.com>

src/network/bearer/qnetworkconfigmanager.cpp

@@ -62,6 +62,7 @@ static void connManager_cleanup()
     // this is not atomic or thread-safe!
     int shutdown = appShutdown.fetchAndStoreAcquire(1);
     Q_ASSERT(shutdown == 0);
+    Q_UNUSED(shutdown);
     QNetworkConfigurationManagerPrivate *cmp = connManager_ptr.fetchAndStoreAcquire(0);
     if (cmp)
         cmp->cleanup();