Cleanup hostname matching in syslogd:

Cleanup hostname matching in syslogd:

1. Hostnames were not treated case insensitively in all cases.

2. The method for stripping hostnames when reading the syslog.conf
   differed from that when finding the hostname of an incoming request.
   This lead to a broken match check.  In my case, it meant I had to
   have '@scooter.smi.example.com.example.com' to have 'logger.example.com'
   properly save messages from 'scooter.smi.sendmail.com'.

3. Add paranoia to cfline() such that it doesn't try to access memory
   outside of the bounds of the f_host string.

4. While I am here, get rid of an outdated comment, argv[{0,1,2}] are now
   checked for NULL after the strdup() calls.

Reviewed by:	dwmalone
MFC after:	1 week