appchooserbutton: filter out applications not supposed to be visible

Ensure NoDisplay=true applications don't end up in the list populated by
GtkAppChooserButton.

https://bugzilla.gnome.org/show_bug.cgi?id=696405

gtk/gtkappchooserbutton.c

@@ -348,6 +348,9 @@ gtk_app_chooser_button_populate (GtkAppChooserButton *self)
     {
       app = l->data;
 
+      if (!g_app_info_should_show (app))
+        continue;
+
       if (default_app != NULL && g_app_info_equal (app, default_app))
         continue;