expunge debugging/nonstandard/trojan horse commands from smtp,

expunge debugging/nonstandard/trojan horse commands from smtp,
logging attempts to use them; log name/address of host from which mail received
("mail from" may not include it or may lie); don't allow debug to affect
permissions locally; change some of the non-system syserrs to syslog at lower
priority; still need to unifdef remaining debug code

SCCS-vsn: usr.sbin/sendmail/src/collect.c 5.5
SCCS-vsn: usr.sbin/sendmail/src/daemon.c 5.28
SCCS-vsn: usr.sbin/sendmail/src/envelope.c 5.16
SCCS-vsn: usr.sbin/sendmail/src/headers.c 5.11
SCCS-vsn: usr.sbin/sendmail/src/sendmail.h 5.14
SCCS-vsn: usr.sbin/sendmail/src/srvrsmtp.c 5.24
SCCS-vsn: usr.sbin/sendmail/src/util.c 5.12