QPID-5887: fix to new txtest2, acknowledge messages in the check phase to ensure queues remain drained for any subsequent runs

git-svn-id: https://svn.apache.org/repos/asf/qpid/trunk@1610958 13f79535-47bb-0310-9956-ffa450edef68
QPID-5887: allow qpid-txtest2 to be run by make test

git-svn-id: https://svn.apache.org/repos/asf/qpid/trunk@1610959 13f79535-47bb-0310-9956-ffa450edef68
QPID-4947: ensure member variable is always initialised

git-svn-id: https://svn.apache.org/repos/asf/qpid/trunk@1610960 13f79535-47bb-0310-9956-ffa450edef68