Restore KDE4 behavior - do not ask for confirmation on logout

Thanks Wolfgnag Bauer (wbauer) for patch

REVIEW: 127128

src/MainWindow.cpp

@@ -531,7 +531,7 @@ bool MainWindow::queryClose()
     // Do not ask for confirmation during log out and power off
     // TODO: rework the dealing of this case to make it has its own confirmation
     // dialog.
-    if (kapp->sessionSaving()) {
+    if (qApp->isSavingSession()) {
         return true;
     }