Make gendeclarations.lua only generate functions from same file

Only last component of filename is checked: this is simple to implement and 
should be enough in all present cases.
Revert "Add a wrapper for msgpack.h"

This reverts commit dbd1453d58d77afbb1fa18d1a06ae67c9b6f54ce.

Obsolete after 1efd2876732b39259ac0032a9d99cfdbf53e6908.