Allow testsuite to run under MSYS/MinGW using native Python (not Cygwin Python).
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.