Vet is a part of go tools since 2013(?) and you don't need to install it
I've tried to install it according to Building section and result is:
➜ Stout git:(master) go get code.google.com/p/go.tools/cmd/vet
package code.google.com/p/go.tools/cmd/vet: unrecognized import path "code.google.com/p/go.tools/cmd/vet" (parse https://code.google.com/p/go.tools/cmd/vet?go-get=1: no go-import meta tags (meta tag github.com/golang/go did not match import path code.google.com/p/go.tools/cmd/vet))
Vet is a part of go tools since 2013(?) and you don't need to install it
I've tried to install it according to Building section and result is: