The project does not use the name "libmsgpack". It variously uses "msgpack" and "msgpack-c", and "msgpackc" for the name of the library.
The patches do no longer apply on-top of the pjsip version we provice. One of the maintainers (@Radvendii @olynch) should have a look what can be done about this. The build has been failing since 2017-07-31…