action: use g_object_class_override_property to add the GAction properties
action: use g_object_class_override_property to add the GAction properties

Using g_object_class_override_property prevents duplication of property
metadata and ensures the properties are compatible with the interface.

The GAction property definitions also changed between glib 2.28 and 2.30
and are now read only, so this commit prevents the GAction properties from
being writable using g_object_set_property.

pwithnall/mx,pwithnall/mx,pwithnall/mx,jonnylamb/mx,clutter-project/mx,pwithnall/mx,clutter-project/mx,jonnylamb/mx,jonnylamb/mx,clutter-project/mx,clutter-project/mx,jonnylamb/mx