Or, use GetFileInformationByHandleEx on Vista or above, and
NtQueryInformationFile under Vista. NtQueryInformationFile
is windows internal function and MS may change its behavior,
but probably we can think it won't happen on WinXP.

# These functions are needed to get real filename from
# open handle to set S_IEXEC.

And provide windows specific functions
  os._open/os._lopen: open windows handle same as
                      CreateFile in os.stat/os.lstat
  os._osfstat: stat for windows handle
  os._close: close windows handle

and if the file is hard link, store windows handle anywhere
in TarFile object. (I created branch for it, but I'm not sure
I can do it)