ssh/terminal: use console functions, types and consts from x/sys/windows

Use GetConsoleMode, SetConsoleMode and GetConsoleScreenBufferInfo and
the corresponding types and constants from golang.org/x/sys/windows
instead of locally defining them.

Change-Id: I69292a47114d071be261ffda6ca620a0b9820d00
Reviewed-on: https://go-review.googlesource.com/52990
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Alex Brainman <alex.brainman@gmail.com>
1 file changed