Stop installing Sendmail.conf by cyrus-sasl2, and it is now installed
by cyrus-sasl2-saslauthd. Since if Sendmail.conf is not installed,
SASL2 uses auxprop by default, it is enough to install Sendmail.conf
by saslauthd port.
- Make saslauthd a separate port to avoid dependency loop between
cyrus-sasl2 and openldap.
- Stop using configuration menu. I believe it ease to maintain
consistency with other SASL related ports.