* tree.h (mark_tree_hashtable): New function.
	* tree.c (mark_tree_hashtable_entry): New function.
	(mark_tree_hashtable): Likewise.

	* tree.c (struct list_hash): Remove.
	(list_hash_table): Make it be an htab.
	(struct list_proxy): New type.
	(list_hash_eq): New function.
	(list_hash_pieces): Renamed from ...
	(list_hash): ... this.
	(list_hash_lookup): Remove.
	(list_hash_add): Remove.
	(hash_tree_cons): Use the generic hashtable.
	(mark_list_hash): Remove.
	(init_tree): Create the hashtable.

From-SVN: r37783