VM: attempt to cancel blocking system calls when ctrl-c is pressed

Occasionally Factor get's stuck waiting on something. Either by a bug or a long timeout. On Linux breaking out of the wait is easy by pressing ctrl-c which causes the call to return with the error EINTR. Windows isn't that easy and you have to tell it to cancel the waits otherwise it doesn't "listen" to ctrl-c. So that's what this patch does.

Btw, Haskell and some other VM's also uses the same approach as in the patch in their Windows ports. So the method should work fine in Factor too.