ANSITerm bug: SIGWINCH does not exist on Windows

[jtfmumm]

In the ANSITerm constructor, a signal handler is set up that does not work on Windows,
as seen in this snippet from the file:

  new create(notify: ANSINotify iso, source: DisposableActor,
    timers: Timers = Timers)
  =>
    """
    Create a new ANSI term.
    """
    _timers = timers
    _notify = consume notify
    _source = source

    // Windows explodes in a swarm of tiny window fragments
    SignalHandler(recover _TermResizeNotify(this) end, Sig.winch())

    _size()

I've opened a PR where I ifdef this line out for Windows.