btree_txn_del
int btree_txn_del(struct btree *bt, struct btree_txn *txn,
btree_txn_del(bt, NULL, key, data)
rc = btree_txn_del(NULL, ns->indx_txn, &key, NULL);
rc = btree_txn_del(NULL, ns->indx_txn, &key, NULL);
rc = btree_txn_del(NULL, ns->data_txn, &key, &data);