Remove a misleading copyright message

The code that commit bb24fa3 moved to a separate file assume_aligned.h was introduced in commit 25e2a55 and developed by employees of MariaDB Corporation.

Author: dr-m

include/assume_aligned.h

@@ -1,5 +1,4 @@
 /*
- Copyright (c) 2000, 2012, Oracle and/or its affiliates.
  Copyright (c) 2020, MariaDB Corporation.
 
  This program is free software; you can redistribute it and/or modify