Update to enable logging via syslog

[se]

Summary

I have contributed a patch to allow logging via syslog instead to a log file to glebius's fork of minidlna.
After testing for some time I think it is time to update the port to add this feature.
Logging via a syslog is selected by the new option "-S".
The rc script does no longer record the PID of the started process, since it uses -S and the PID is only required to sending HUP after rotation of the log file if not using by syslog.
Filtering provided by syslog allows sending different records of different severity to separate files.
This patch does not include an update to the man-page, a pull request will be sent to upstream (requiring an update of the commit hash referenced in the Makefile).

Test Plan

Apply patch to /usr/ports/net/minidlna and rebuild minidlna.
Test logging via syslog.
Logging to a disk file is still available.

Filtering of log entries can be controlled with syslog.conf lines, e.g.:
!minidlnad
*.warn /var/log/minidlna.log

[glebius]

Oh, this review really confused me. My memory was that I still owe you reviewing the patch at github, and it is not in the master branch. But the port update assumes the github pull request was merged. So it looks like our ports github glue allows to specify revisions from pull requests! I really would prefer to finish on github and just have it in master there. I will try to get back to that on weekend.