Make gtk_tree_view_enable_model_drag_[source|dest] compatible with

Make gtk_tree_view_enable_model_drag_[source|dest] compatible with

	* gtk/gtktreeview.c: (destroy_info), (set_destination_row),
	(gtk_tree_view_maybe_begin_dragging_row),
	(gtk_tree_view_set_reorderable),
	(gtk_tree_view_enable_model_drag_source),
	(gtk_tree_view_enable_model_drag_dest),
	(gtk_tree_view_unset_rows_drag_source),
	(gtk_tree_view_unset_rows_drag_dest): Make
	gtk_tree_view_enable_model_drag_[source|dest] compatible with
	gtk_drag_[source|dest]_add_*_targets. Bug #506853.

svn path=/trunk/; revision=20349