[Unison-hackers] prompts require newline in Cygwin

[Andrew Schulman]

> If you're willing to recompile, try changing
> 
>   let supportSignals = Util.osType = `Unix (*|| Util.isCygwin*)
> 
> in uitext.ml to
> 
>   let supportSignals = Util.osType = `Unix || Util.isCygwin
> 
> and see if things improve...

This applies to version 2.40, but not 2.27 or 2.32.  It seems that the
uitext.ml code has been rewritten since 2.32 - there was no supportSignals
flag then.  I took a quick look at it and I think I can probably work out
what change is needed for Cygwin, but if you can easily suggest the
comparable patch for 2.32 and earlier, please do.  Thanks, Andrew.