Revert "ssh/terminal: account for win32 api changes"

This reverts commit CL 196897 (commit cf60e62b0da83)

Reason for revert: we're reverting the API change instead
in https://go-review.googlesource.com/c/sys/+/197597

Change-Id: I41741c85bb7a07b9ce13264ebb26ee3f968772fa
Reviewed-on: https://go-review.googlesource.com/c/crypto/+/197598
Reviewed-by: Bryan C. Mills <bcmills@google.com>
Run-TryBot: Bryan C. Mills <bcmills@google.com>