Pass the full list of pools to acquire_address, enumerate in providers

If the provider has access to the full pool list, it can enumerate
them twice, for example to search for existing leases first, and
only search for new leases in a second step.

Fixes lease enumeration in attr-sql using multiple pools.

src/libcharon/plugins/unit_tester/tests/test_pool.c

@@ -27,6 +27,7 @@ static void* testing(void *thread)
 	int i;
 	host_t *addr[ALLOCS];
 	identification_t *id[ALLOCS];
+	linked_list_t *pools;
 
 	/* prepare identities */
 	for (i = 0; i < ALLOCS; i++)
@@ -37,17 +38,23 @@ static void* testing(void *thread)
 		id[i] = identification_create_from_string(buf);
 	}
 
+	pools = linked_list_create();
+	pools->insert_last(pools, "test");
+
 	/* allocate addresses */
 	for (i = 0; i < ALLOCS; i++)
 	{
 		addr[i] = hydra->attributes->acquire_address(hydra->attributes,
-													 "test", id[i], NULL);
+													 pools, id[i], NULL);
 		if (!addr[i])
 		{
+			pools->destroy(pools);
 			return (void*)FALSE;
 		}
 	}
 
+	pools->destroy(pools);
+
 	/* release addresses */
 	for (i = 0; i < ALLOCS; i++)
 	{