add_derived_key
ret = add_derived_key((krb5_keyblock *)key, usage,
rv = add_derived_key(key, usage, DK_ENCR_KEY_BYTE,
rv = add_derived_key(key, usage, DK_HASH_KEY_BYTE,
krb5_error_code add_derived_key(krb5_keyblock *, krb5_keyusage, uchar_t,