bugfix for OSFS.listdir on win32
bugfix for OSFS.listdir on win32

pombreda/pyfilesystem,rivenz/pyfilesystem,pmitros/pyfs,pmitros/pyfs,PyFilesystem/pyfilesystem,Konubinix/pyfilesystem,piranna/pyfilesystem,zopyx/pyfilesystem,flying-circus/pyfilesystem