syslogd(8) counts dropped UDP packets.

syslogd(8) counts dropped UDP packets.

Now that syslogd handles delayed DNS lookups, also count dropped
packets to UDP loghosts.  Although not every outgoing UDP packet
dropped along the path can be detected, the message makes the admin
aware that there is a local blind spot during startup.
Improve debug and log messages, especially if UDP logging is shut
down permanently.  Also do not print 'last message repeated' if the
message was dropped.

OK deraadt@