This reverts CL 164837 (0f64db555a)
Reason for revert: breaks vetall against tip (and thus go tip's trybots)
Change-Id: I5109691481f44a9807675a6139f1619a03b0c58d
Reviewed-on: https://go-review.googlesource.com/c/tools/+/165039
Reviewed-by: Dmitri Shuralyov <dmitshur@golang.org>
Reviewed-by: Andrew Bonventre <andybons@golang.org>