clamdscan: replace immunity check with naught test
clamdscan: replace immunity check with naught test

immunity check was disabled by default, as it wasn't a good policy. OTOH, a naughty check is a sensible default, as we can skip processing on messages we already decided to reject.

smtpd/qpsmtpd,smtpd/qpsmtpd,priyadi/qpsmtpd,sieutruc/qpsmtpd,sieutruc/qpsmtpd,salvis/qpsmtpd,sieutruc/qpsmtpd,msimerson/qpsmtpd,msimerson/qpsmtpd,priyadi/qpsmtpd,salvis/qpsmtpd,priyadi/qpsmtpd