check _MSC_VER is defined before comparing value
check _MSC_VER is defined before comparing value

ebu/ebu-libmxf,stuarthicks/libmxf,stuarthicks/libmxf,Limecraft/ebu-libmxf,stuarthicks/libmxf,ebu/ebu-libmxf,Limecraft/ebu-libmxf,Limecraft/ebu-libmxf,ebu/ebu-libmxf,stuarthicks/libmxf,ebu/ebu-libmxf