Update to 3.3.1.

Peter Czanik <czanik@balabit.hu>, our syslog-ng upline, recommended we put
3.3.1 into syslog-ng-devel first, then commit to sysutils/syslog-ng in a week.

Commit to sysutils/syslog-ng: 1 week

Submitted by: Peter Czanik <czanik@balabit.hu>, our syslog-ng upline