configure: remove mingw fseeko/ftello redefines
configure: remove mingw fseeko/ftello redefines

The same file i/o function as msvc would be used.

ebu/ebu-libmxfpp,ebu/ebu-libmxfpp,Limecraft/ebu-libmxfpp,stuarthicks/libmxfpp,stuarthicks/libmxfpp,ebu/ebu-libmxfpp,stuarthicks/libmxfpp,Limecraft/ebu-libmxfpp,Limecraft/ebu-libmxfpp