Add copyright header to make.bat

The Open Source Automated Checkup flags make.bat as the only source file
in the repo missing a copyright header (all other scanned files already
carry one). Adds the standard Meta OSS MIT header using batch-file
comment syntax.

Author: caglarpir

make.bat

@@ -1,3 +1,8 @@
+@REM Copyright (c) Meta Platforms, Inc. and affiliates.
+@REM
+@REM This source code is licensed under the MIT license found in the
+@REM LICENSE file in the root directory of this source tree.
+
 @echo off