Add a hack to block calls to certain introspected functions

This is useful for keeping people from using methods that only fail in
certain circumstances, by making them fail in all circumstances
instead.

https://bugzilla.gnome.org/show_bug.cgi?id=618918

src/shell-global.h

@@ -96,6 +96,11 @@ guint32 shell_global_get_current_time (ShellGlobal *global);
 
 GAppLaunchContext *shell_global_create_app_launch_context (ShellGlobal *global);
 
+gboolean shell_global_set_property_mutable (ShellGlobal *global,
+                                            const char  *object,
+                                            const char  *property,
+                                            gboolean     mutable);
+
 G_END_DECLS
 
 #endif /* __SHELL_GLOBAL_H__ */