- KRB5_PRINCIPAL_PARSE_IGNORE_REALM: MIT compatible
- KRB5_PRINCIPAL_PARSE_NO_DEF_REALM: Don't default the realm
The first ignores the realm if present.
The second does not impute the default realm if no realm is given and
leaves the realm NULL. This will be used in kinit to determine whether
the user provided a realm or not, and if not we may use the user_realm,
or find the realm via the keytab.