Update copyright headers in build/, build_overrides/, and buildtools/

The methodology used to generate this CL is documented in
https://crbug.com/1098010#c34.

An earlier version of this CL, https://crrev.com/c/3879808,
was reverted due to an issue that was resolved with
https://crrev.com/c/3881211.

No-Try: true
Bug: 1098010
Change-Id: I91174ff0a9dd8b6dee79e6cba8209b614ce2b712
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/3884220
Reviewed-by: Mark Mentovai <[email protected]>
Auto-Submit: Avi Drissman <[email protected]>
Owners-Override: Avi Drissman <[email protected]>
Commit-Queue: Mark Mentovai <[email protected]>
Cr-Commit-Position: refs/heads/main@{#1044745}
diff --git a/build/timestamp.gni b/build/timestamp.gni
index 4d805c0..b9b57d9 100644
--- a/build/timestamp.gni
+++ b/build/timestamp.gni
@@ -1,4 +1,4 @@
-# Copyright 2018 The Chromium Authors. All rights reserved.
+# Copyright 2018 The Chromium Authors
 # Use of this source code is governed by a BSD-style license that can be
 # found in the LICENSE file.
 #