Cleanup/simplify copyright info

Historically we have been (more-or-less consistently, sometimes forgetting
some files) updating the end year of the copyright statements at the
beginning of a new year.

We're naturally not alone in that.  Recently this was discussed in curl, and
it turns out that copyright years are not really required:

https://daniel.haxx.se/blog/2023/01/08/copyright-without-years/

So drop the years and simplify the copyright statements.  While we're at it,
also ensure the same syntax (capital C, email address) is used everywhere.

Signed-off-by: Peter Korsgaard <peter@korsgaard.com>
Signed-off-by: Yann E. MORIN <yann.morin.1998@free.fr>
diff --git a/Makefile b/Makefile
index efa0b2a..8517d56 100644
--- a/Makefile
+++ b/Makefile
@@ -1,8 +1,6 @@
 # Makefile for buildroot
 #
-# Copyright (C) 1999-2005 by Erik Andersen <andersen@codepoet.org>
-# Copyright (C) 2006-2014 by the Buildroot developers <buildroot@uclibc.org>
-# Copyright (C) 2014-2020 by the Buildroot developers <buildroot@buildroot.org>
+# Copyright (C) the Buildroot developers <buildroot@buildroot.org>
 #
 # This program is free software; you can redistribute it and/or modify
 # it under the terms of the GNU General Public License as published by