QPID-5255: Add missing licenses in qpid/cpp tree.

Added licenses to:

qpid/cpp/src/qmf2.pc.in
qpid/cpp/src/qpid.linkmap
qpid/cpp/src/qpid.pc.in

From trunk r1551620

git-svn-id: https://svn.apache.org/repos/asf/qpid/branches/0.26@1551622 13f79535-47bb-0310-9956-ffa450edef68