QPID-5427: Critical log messages should not ever be disabled

git-svn-id: https://svn.apache.org/repos/asf/qpid/trunk@1555201 13f79535-47bb-0310-9956-ffa450edef68
QPID-5415: Implement control of internal log output in qpid::messaging API

git-svn-id: https://svn.apache.org/repos/asf/qpid/trunk@1555202 13f79535-47bb-0310-9956-ffa450edef68