all: fix printf(var) mistakes detected by latest printf checker
These will cause build failures once we vendor x/tools.
In once case I renamed a function err to errf to indicate
that it is printf-like.
Updates golang/go#68796
Change-Id: I04d57b34ee5362f530554b7e8b817f70a9088d12
Reviewed-on: https://go-review.googlesource.com/c/go/+/610739
Commit-Queue: Alan Donovan <adonovan@google.com>
Reviewed-by: Robert Findley <rfindley@google.com>
LUCI-TryBot-Result: Go LUCI <golang-scoped@luci-project-accounts.iam.gserviceaccount.com>
Reviewed-by: Tim King <taking@google.com>
Auto-Submit: Alan Donovan <adonovan@google.com>