txmpp is a C++ XMPP library created from the non-XEP-0166 portions of libjingle with various bits removed and tweaked.
The motivating factor for "creating" txmpp was the lack of permissively licenced alternatives.
If you don't mind a library with a copyleft license you might also try gloox.
make
make install
See the src/examples directory.
This work is licensed under the New BSD License (see the LICENSE file).