csd: Always raise on primary titlebar click

This matches more closely what typical window managers do.
Pointed out in
https://bugzilla.redhat.com/show_bug.cgi?id=1158472

gtk/gtkwindow.c

@@ -1457,6 +1457,9 @@ multipress_gesture_pressed_cb (GtkGestureMultiPress *gesture,
 
   event_widget = gtk_get_event_widget ((GdkEvent*) event);
 
+  if (region == GTK_WINDOW_REGION_TITLE)
+    gdk_window_raise (gtk_widget_get_window (widget));
+
   switch (region)
     {
     case GTK_WINDOW_REGION_CONTENT: