Explicitly #include <ostream>

libchrome will soon include Chromium change crrev.com/1092231, which
removes an include of <ostream> from base/numerics/safe_conversions.h.

cbor's writer.cc needs such an include for NOTREACHED() << ...

Also update copyright notice to pass presubmit checks.

BUG=b:266510143
TEST=emerge cbor

Change-Id: If6464ef84f998b4baea627c780d0d31f57d66656
Reviewed-on: https://chromium-review.googlesource.com/c/chromiumos/platform/cbor/+/4189742
Auto-Submit: Georg Neis <neis@chromium.org>
Tested-by: Georg Neis <neis@chromium.org>
Commit-Queue: Georg Neis <neis@chromium.org>
Reviewed-by: Jora Jacobi <jora@google.com>
diff --git a/writer.cc b/writer.cc
index ff6a6f5..71f9f3c 100644
--- a/writer.cc
+++ b/writer.cc
@@ -1,10 +1,11 @@
-// Copyright 2017 The Chromium OS Authors. All rights reserved.
+// Copyright 2017 The ChromiumOS Authors
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "cbor/writer.h"
 
 #include <optional>
+#include <ostream>
 #include <string>
 
 #include "base/check_op.h"