page file: simplify disk_file_size function
page file: simplify disk_file_size function

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