all: go fmt ./...

Make all our package sources use Go 1.17 gofmt format
(adding //go:build lines).

Not strictly necessary but will avoid spurious changes
as files are edited.

Part of //go:build change (#41184).
See https://golang.org/design/draft-gobuild

Change-Id: I22803ea9e936fbb08984a64155302f47e181de27
Reviewed-on: https://go-review.googlesource.com/c/oauth2/+/294420
Trust: Russ Cox <rsc@golang.org>
Trust: Cody Oss <codyoss@google.com>
Run-TryBot: Russ Cox <rsc@golang.org>
TryBot-Result: Go Bot <gobot@golang.org>
Reviewed-by: Cody Oss <codyoss@google.com>

google/appengine_gen1.go

@@ -2,6 +2,7 @@
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
+//go:build appengine
 // +build appengine
 
 // This file applies to App Engine first generation runtimes (<= Go 1.9).

google/appengine_gen2_flex.go

@@ -2,6 +2,7 @@
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
+//go:build !appengine
 // +build !appengine
 
 // This file applies to App Engine second generation runtimes (>= Go 1.11) and App Engine flexible.

internal/client_appengine.go

@@ -2,6 +2,7 @@
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
+//go:build appengine
 // +build appengine
 
 package internal