https://go-review.googlesource.com/c/go/+/120875 changed the name
of types.NewInterface2 to NewInterfaceType. Adjust x/tools code to
match new API.
For golang/go#25301.
Change-Id: I21e13566f7c88591a16ce461cb4cce8901980b05
Reviewed-on: https://go-review.googlesource.com/120895
Run-TryBot: Robert Griesemer <gri@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Josh Bleecher Snyder <josharian@gmail.com>
Reviewed-by: Ian Lance Taylor <iant@golang.org>