sysutils/syslog-ng: Update to 4.8.0

Patch was created and tested by our upstream representative
Peter Czanik.

As Peter explains to me in an email this is the first version of
syslog-ng after the Axoflow fork.

Submitted by:	Peter Czanik (CzP) <peter.czanik@oneidentity.com>
		Balabit (a OneIdentity company) / syslog-ng upstream