implement stdio exec on win32

[wwiv]

Right now it only works on *nix, need to figure out how to make it work on win32. just setting the handles didn't do it.

[wwiv]

https://support.microsoft.com/en-us/help/190351/how-to-spawn-console-processes-with-redirected-standard-handles

[wwiv]

https://github.com/diegocr/netcat/blob/master/doexec.c

[wwiv]

http://edn.embarcadero.com/article/10387 has a good example, really this is just like the syncfoss case, except we write to a names pipe that the stdio stdin handles were pointed to

[wwiv]

Also https://docs.microsoft.com/en-us/windows/win32/procthread/creating-a-child-process-with-redirected-input-and-output