Update golang.org/x dependencies to their latest tagged versions.

Change-Id: I81218876c6b66a0aa17beb6e0917d60cd6987100
Reviewed-on: https://go-review.googlesource.com/c/tools/+/603419
Auto-Submit: Gopher Robot <gobot@golang.org>
LUCI-TryBot-Result: Go LUCI <golang-scoped@luci-project-accounts.iam.gserviceaccount.com>
Reviewed-by: Dmitri Shuralyov <dmitshur@google.com>
Reviewed-by: David Chase <drchase@google.com>