Handle the logfiles in newsyslog and syslogd conditionally, based on
src.conf(5) knobs

This will allow consumers of FreeBSD to use the unmodified configuration
files out of the box more than previously.

Both newsyslog.conf and syslog.conf:

• /var/log/lpd-errs (MK_LPR != no)
• /var/log/ppp.log (MK_PPP != no)
• /var/log/xferlog (MK_FTP != no)

newsyslog.conf:

• /var/log/amd.log (MK_AMD != no)
• /var/log/pflog (MK_PF != no)
• /var/log/sendmail.st (MK_SENDMAIL != no)

MFC after: 3 weeks
Sponsored by: Dell EMC Isilon