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: I01667f826428426a39c84717d02efa25fa44553c
Reviewed-on: https://go-review.googlesource.com/c/sys/+/294490
TryBot-Result: Go Bot <gobot@golang.org>
Reviewed-by: Keith Randall <khr@golang.org>
Reviewed-by: Josh Bleecher Snyder <josharian@gmail.com>
Reviewed-by: Matt Layher <mdlayher@gmail.com>
Trust: Josh Bleecher Snyder <josharian@gmail.com>
Trust: Russ Cox <rsc@golang.org>
Run-TryBot: Josh Bleecher Snyder <josharian@gmail.com>
Run-TryBot: Russ Cox <rsc@golang.org>
diff --git a/unix/timestruct_test.go b/unix/timestruct_test.go
index 1a72fdb..e39df4c 100644
--- a/unix/timestruct_test.go
+++ b/unix/timestruct_test.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 aix || darwin || dragonfly || freebsd || linux || netbsd || openbsd || solaris
 // +build aix darwin dragonfly freebsd linux netbsd openbsd solaris
 
 package unix_test