Fix crash cancelling render while building object instance in

raytree, object could still be added after it was already freed.

(merge from render25 branch)

source/blender/render/intern/source/rayshade.c

@@ -370,6 +370,10 @@ static void makeraytree_single(Render *re)
 		if(has_special_rayobject(re, obi))
 		{
 			RayObject *obj = makeraytree_object(re, obi);
+
+			if(test_break(re))
+				break;
+
 			RE_rayobject_add( re->raytree, obj );
 		}
 		else