win32 file: set correct file open access and share modes
win32 file: set correct file open access and share modes

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