cp -r x/tools/cmd/vet cmd/vet without any changes.
The next change will adjust the source to use std
repo go/types and friends.

This may (temporarily) break the build; the next
commit (immediately following) will fix it. We do
it in two commits so that we can see the manual
changes.

Change-Id: Ic45dab7066f13923e21f8c61200c8c3fd447b171
Reviewed-on: https://go-review.googlesource.com/10694Reviewed-by: Rob Pike <r@golang.org>