newsyslog.conf: Restrict included files in default config to [!.]*.conf
The new default config will only include files from the following
directories which end with '.conf' and do not beginning with a '.'
This matches the syslog.conf(5) functionality, and also prevents '.sample' or
'.pkgnew' files being included. This is important for ports which install files
in /usr/local/etc/newsyslog.conf.d/ and also for pkgbase.