Update x/tools.

For golang/go#64973

Change-Id: Icfc2f5327e0f2154e65fb366647078538bb4190f
Reviewed-on: https://go-review.googlesource.com/c/tools/+/564656
Reviewed-by: Alan Donovan <adonovan@google.com>
Auto-Submit: Robert Findley <rfindley@google.com>
LUCI-TryBot-Result: Go LUCI <golang-scoped@luci-project-accounts.iam.gserviceaccount.com>