This patch is based on a similar one "Enable timeout in Windows
and don't require cygwin python" by Esa Ilari Vuokko. It seems
like timeout is always built on Windows so I rearranged the logic
there to make the code clearer, Esa's patch required the user to
uncomment the MinGW-specific logic in order for it to work; this
patch does not have the MinGW-specific logic commented out.

I tested this on the trunk in Ubuntu 6.06 on i686 (VMWare).
I tested this on the trunk and ghc-6.6 branch on Windows i686.