assign something to "prev" so that removing tag info succeeds. Part of

assign something to "prev" so that removing tag info succeeds. Part of

2002-04-30  Havoc Pennington  <hp@redhat.com>

	* gtk/gtktextbtree.c (gtk_text_btree_remove_tag_info): assign
	something to "prev" so that removing tag info succeeds.
	Part of #77301

	* gtk/gtktextbtree.c (_gtk_text_btree_unref): reorder so that it
	unrefs the tag table first, so that the btree is in a consistent
	state when we're removing tags from it.

	* gtk/gtktexttagtable.c (_gtk_text_tag_table_remove_buffer): strip
	all tags in the tag table out of the buffer. #77301