NO-JIRA: Get rid of valgrind "rechable" block in logging statements.

Each logging statement was allocating and not freeing a string, generating a
huge number of harmless but annoying "blocks are still reachable".

Fixed so the strings are freed at static destructor time.

git-svn-id: https://svn.apache.org/repos/asf/qpid/trunk@1565431 13f79535-47bb-0310-9956-ffa450edef68