Add the SetConsoleMode and GetConsoleScreenBufferInfo functions, as well
as the corresponding types and constants. For details see:

  https://docs.microsoft.com/en-us/windows/console/setconsolemode
  https://docs.microsoft.com/en-us/windows/console/getconsolescreenbufferinfo
  https://docs.microsoft.com/en-us/windows/console/console-screen-buffer-info-str

Change-Id: I17dcd62ffde12b5c94e1245b6836d067aea3dc6e
Reviewed-on: https://go-review.googlesource.com/52670
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Alex Brainman <alex.brainman@gmail.com>