pass the size of the dst buffer to strlcat, not the source; pointed
out by clang

OK kettenis

From a syslog perspective it does not make sense to log fatal and
warn with the same severity. Switch log_warn() to LOG_ERR and keep
fatal() at LOG_CRIT.
OK reyk@ florian@

Add OpenBSD RCS id.

Rework logging.

Use log.c like in many other daemons, with small additions to maintain
a log queue (useful to dump a single log line with several logging
statements). Use log.c to dump the internal state, and remove the -R
option (a similar feature will be implemented differently soon).

The end goal is to avoid touching the filesystem and use much tighter
pledge(2) restrictions.

Tested by Freddy Dissaux.