Set a console Ctrl handler for Windows

Set a console Ctrl handler for Windows

Install a Lisp callback using SetConsoleCtrlHandler, allowing users
to interrupt SBCL using C-c in the Windows console.

We cannot currently control the size of the stack available to us in
this handler, but since we are mainly only calling INTERRUPT-THREAD,
even a small stack might be sufficient for our purposes.

Thanks to Anton Kovalenko.