kadm5_modify_principal()
modifies a principal according to the given
options. Allowed are the following options:
KADM5_PRINC_EXPIRE_TIME, KADM5_PW_EXPIRATION, KADM5_ATTRIBUTES,
KADM5_MAX_LIFE, KADM5_KVNO, KADM5_POLICY, KADM5_CLEARPOLICY,
KADM5_MAX_RLIFE, KADM5_FAIL_AUTH_COUNT.