TPCnv libraries declare Gaudi plugin factories for the TP converters.
Normally, the TPCnv libraries should not be linked against libraries
other than the EventPool libraries.  However, it is possible for one
TPCnv library to link against another TPCnv library.
In that case, genconf may emit warnings that one library's factory
is visible from another.  Clean up by moving TPCnv factories into their
own libraries (linked against the corresponding TPCnv library).