window: Unfreeze window on unmap

Make sure to keep parity with the number of times we froze the window
when we unmap it.
Otherwise it will permanently stay frozen after being remapped.

https://bugzilla.gnome.org/show_bug.cgi?id=766643
https://bugzilla.mozilla.org/show_bug.cgi?id=1225044

gtk/gtkwindow.c

@@ -6350,7 +6350,11 @@ gtk_window_unmap (GtkWidget *widget)
   gtk_widget_set_mapped (widget, FALSE);
   gdk_window_withdraw (gdk_window);
 
-  priv->configure_request_count = 0;
+  while (priv->configure_request_count > 0)
+    {
+      priv->configure_request_count--;
+      GDK_PRIVATE_CALL (gdk_window_thaw_toplevel_updates) (_gtk_widget_get_window (widget));
+    }
   priv->configure_notify_received = FALSE;
 
   /* on unmap, we reset the default positioning of the window,