Add default_shaper_list to shape_plan

src/hb-shape-plan-private.hh

@@ -39,6 +39,7 @@ struct hb_shape_plan_t
   hb_object_header_t header;
   ASSERT_POD ();
 
+  hb_bool_t default_shaper_list;
   hb_face_t *face;
   hb_segment_properties_t props;
 

src/hb-shape-plan.cc

@@ -100,6 +100,7 @@ hb_shape_plan_create (hb_face_t                     *face,
     return hb_shape_plan_get_empty ();
 
   hb_face_make_immutable (face);
+  shape_plan->default_shaper_list = shaper_list == NULL;
   shape_plan->face = hb_face_reference (face);
   shape_plan->props = *props;
 
@@ -114,6 +115,7 @@ hb_shape_plan_get_empty (void)
   static const hb_shape_plan_t _hb_shape_plan_nil = {
     HB_OBJECT_HEADER_STATIC,
 
+    TRUE, /* default_shaper_list */
     NULL, /* face */
     _HB_BUFFER_PROPS_DEFAULT, /* props */