Fixes vetall build broken by CL 38693.

Change-Id: I5c98f2164e0c7bb43f022c363b3b7c0650c4bcbe
Reviewed-on: https://go-review.googlesource.com/39916
Run-TryBot: Josh Bleecher Snyder <josharian@gmail.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Rob Pike <r@golang.org>