8.6.2: improved error return messages; better error handling on

8.6.2: improved error return messages; better error handling on
hung connections or the name server is down; add "vendor code" on V line;
fix some X-Authentication-Warning: problems; portability fixes

SCCS-vsn: usr.sbin/sendmail/src/READ_ME 8.29
SCCS-vsn: usr.sbin/sendmail/src/usersmtp.c 8.11
SCCS-vsn: usr.sbin/sendmail/src/main.c 8.30
SCCS-vsn: usr.sbin/sendmail/src/conf.h 8.38
SCCS-vsn: usr.sbin/sendmail/src/collect.c 8.5
SCCS-vsn: usr.sbin/sendmail/src/version.c 8.6.2.1
SCCS-vsn: usr.sbin/sendmail/src/sendmail.h 8.24
SCCS-vsn: usr.sbin/sendmail/src/savemail.c 8.14
SCCS-vsn: usr.sbin/sendmail/src/TODO 8.6
SCCS-vsn: usr.sbin/sendmail/src/srvrsmtp.c 8.17
SCCS-vsn: usr.sbin/sendmail/src/readcf.c 8.13
SCCS-vsn: usr.sbin/sendmail/src/deliver.c 8.31
SCCS-vsn: usr.sbin/sendmail/src/conf.c 8.41
SCCS-vsn: usr.sbin/sendmail/src/alias.c 8.17
SCCS-vsn: usr.sbin/sendmail/src/map.c 8.17