Add Windows CI support (help wanted: Cygwin)

[ianfixes]

This can't go forward unless/until someone knows how to invoke aclocal in a Cygwin environment

[retokromer]

Sorry, I cannot help on this one, because building on Cygwin has ever been a failure-prone task to me… I guess, you should consider cross-compiling from Linux either on a virtual machine, via dual-boot or from another computer.

[davewongillies]

@ianfixes I've gotten it finding the commands now in #14 , just blocked on the configure not being able to find libraries.

[ianfixes]

It looks like the error is related to not being able to find a terminal library: https://stackoverflow.com/q/12290783/2063546

But that's confusing, since we manually install libncurses-devel at the beginning of the build process.

[davewongillies]

@ianfixes here's a working build. It looks like the extra C:\cygwin\bin in the $PATH was causing the issues: https://github.com/davewongillies/cxmon/blob/appveyor/appveyor.yml#L8

[ianfixes]

😮 THANK YOU!

I could use your help on emaculation/macemu#106 too...