int case_compare (const struct ccase *, const struct ccase *,
const struct variable *const *, size_t var_cnt);
int case_compare_2dict (const struct ccase *, const struct ccase *,
int case_compare (const struct ccase *, const struct ccase *,
const struct variable *const *, size_t var_cnt);
int case_compare_2dict (const struct ccase *, const struct ccase *,