[support] Patch software under Windows

[John Fletcher]

Thanks for the recommendations everyone.  I got mingw working with a bit of
effort - not exactly your usual Windows "bouncing ball" installation
process.  I was tempted to try unxutils but I'm running Vista so I'll stick
with mingw for the moment.

> I highly suggest MSYS from http://www.mingw.org.  But there is also 
> http://unxutils.sourceforge.net/ which includes a patch command.