[gtk/matthiasc/for-master] gtk-demo: Plug a leak

[Matthias Clasen <matthiasc src gnome org>]

commit 9d15e64f0b37561a89e21675e12efa56ac44c8b6
Author: Matthias Clasen <mclasen redhat com>
Date:   Mon Jun 1 15:16:02 2020 -0400

    gtk-demo: Plug a leak
    
    We were leaking a reference to the settings demo.
    This showed up as gtk4-demo --run listview_settings
    not exiting when the window is closed.

 demos/gtk-demo/listview_settings.c | 2 ++
 1 file changed, 2 insertions(+)
---
diff --git a/demos/gtk-demo/listview_settings.c b/demos/gtk-demo/listview_settings.c
index deecdaeb57..c00024a68e 100644
--- a/demos/gtk-demo/listview_settings.c
+++ b/demos/gtk-demo/listview_settings.c
@@ -343,6 +343,8 @@ do_listview_settings (GtkWidget *do_widget)
       sorter = gtk_string_sorter_new (gtk_property_expression_new (SETTINGS_TYPE_KEY, NULL, "name"));
       gtk_column_view_column_set_sorter (name_column, sorter);
       g_object_unref (sorter);
+
+      g_object_unref (builder);
     }
 
   if (!gtk_widget_get_visible (window))