crgetsgid
extern gid_t crgetsgid(const cred_t *);
un32.prcred.pr_sgid = crgetsgid(cp);
un.prcred.pr_sgid = crgetsgid(cp);
tlcred->tc_sgid = crgetsgid(cr);
gid != crgetsgid(credp)) {
extern gid_t crgetsgid(const cred_t *);