all: fix some typos in comments
This change fixes some typographic errors that I found in various packages.
Change-Id: Ie2d0316f0137d6521496d389a9777659ae22128b
GitHub-Last-Rev:
0307b03d50f664a00a4afa5afa08a35efb7f3045
GitHub-Pull-Request: golang/go#66917
Reviewed-on: https://go-review.googlesource.com/c/go/+/580077
LUCI-TryBot-Result: Go LUCI <golang-scoped@luci-project-accounts.iam.gserviceaccount.com>
Reviewed-by: Cherry Mui <cherryyz@google.com>
Reviewed-by: David Chase <drchase@google.com>
Reviewed-by: Rob Pike <r@golang.org>
Reviewed-by: Emmanuel Odeke <emmanuel@orijtech.com>
Commit-Queue: Ian Lance Taylor <iant@golang.org>
Auto-Submit: Ian Lance Taylor <iant@golang.org>