Make AQMP support optional. AQMP support, which was prior to this
revision not optional, caused syslog-ng to fail to build with
LibreSSL. Users of LibreSSL should disable AQMP support.

PR: 225380
Submitted by: Peter Czanik (CzP) <peter.czanik@balabit.com>

		Balabit / syslog-ng upstream

MFH: 2018Q1