QPID-4552: Messaging examples now build.

The commit for QPID-4372 moved the messaging examples to CMake but then
stopped building the binaries themselves. This patch restores the
building of the examples.

git-svn-id: https://svn.apache.org/repos/asf/qpid/trunk@1440423 13f79535-47bb-0310-9956-ffa450edef68