mdb_path_alloc
mdb.m_ipath = mdb_path_alloc(path, &mdb.m_ipathlen);
mdb.m_lpath = mdb_path_alloc(path, &mdb.m_lpathlen);
extern const char **mdb_path_alloc(const char *, size_t *);
p = mdb_path_alloc(mdb.m_root, &len);
p = mdb_path_alloc(old_root, &len);