Detect generated library filename instead of computing from version number.
Detect generated library filename instead of computing from version number.

Beacuse it's wrong in general -- filename is related to SONAME not version.

johnty/libmapper,johnty/libmapper,malloch/libmapper,libmapper/libmapper,libmapper/libmapper,malloch/libmapper,johnty/libmapper,radarsat1/libmapper,libmapper/libmapper,johnty/libmapper,johnty/libmapper,radarsat1/libmapper,malloch/libmapper,libmapper/libmapper,radarsat1/libmapper,malloch/libmapper,libmapper/libmapper,radarsat1/libmapper,malloch/libmapper,libmapper/libmapper,radarsat1/libmapper,malloch/libmapper