Validate failures on Windows 7

[Edward Z. Yang]

It looks like this is just http://hackage.haskell.org/trac/ghc/ticket/2628 .
I'll submit a patch that marks these as expected failures.

I've also asked on StackOverflow if there's something better we can
do in this case:

    http://stackoverflow.com/questions/3648711/detect-nul-file-descriptor-isatty-is-bogus

Excerpts from Edward Z. Yang's message of Sat Sep 04 14:19:44 -0400 2010:
> Hello all,
> 
> I'm getting the following validate failures on a fresh checkout
> of Darcs HEAD run on Windows 7:
> 
> OVERALL SUMMARY for test run started at The current date is: Sat 09/04/2010 
> Enter the new date: (mm-dd-yy) 
>     2540 total tests, which gave rise to
>    10708 test cases, of which
>        0 caused framework failures
>     8464 were skipped
> 
>     2146 expected passes
>       83 expected failures
>        2 unexpected passes
>       13 unexpected failures
> 
> Unexpected passes:
>    hsc2hs001(normal)
>    hsc2hs002(normal)
> 
> Unexpected failures:
>    2636(normal)
>    3890(normal)
>    4198(normal)
>    ghc-e001(normal)
>    ghc-e002(normal)
>    ghc-e003(normal)
>    ghc-e004(normal)
>    ghc-e005(normal)
>    mdo003(normal)
>    mod166(normal)
>    outofmem(normal)
>    process003(normal)
>    process006(normal)
> 
> Is this a known issue?
> 
> Cheers,
> Edward