* cfg.c: Include alloc-pool.h
(edge_pool): New pool.
(bb_pool): New pool.
(first_deleted_edge): Remove.
(first_deleted_block): Remove.
(init_flow): Alloc/free the pools.
(free_edge): Use pools.
(alloc_block): Ditto.
(expunge_block): Ditto.
(cached_make_edge): Ditto.
* et-forest.c: Include alloc-pool.h.
(struct et_forest): Add node_pool and occur_pool.
(et_forest_create): Create the new pools.
(et_forest_delete): Delete them.
(et_forest_add_node): Allocate and free using pools.
(et_forest_add_edge): Ditto.
(et_forest_remove_node): Ditto.
(et_forest_remove_edge): Ditto.