btree_compact_tree
node->n_pgno = btree_compact_tree(bt, node->n_pgno, btc);
next = btree_compact_tree(bt, next, btc);
*pnext = btree_compact_tree(bt, *pnext, btc);
static pgno_t btree_compact_tree(struct btree *bt, pgno_t pgno,
root = btree_compact_tree(bt, bt->meta.root, btc);