aufs: tiny, update the year in Copyright

Signed-off-by: J. R. Okajima <hooanon05g@gmail.com>
(cherry picked from commit 56b4b776c84f364384971c4cdfd66b4a2f0696d4)

fs/aufs/wkq.h

 /* SPDX-License-Identifier: GPL-2.0 */
 /*
- * Copyright (C) 2005-2019 Junjiro R. Okajima
+ * Copyright (C) 2005-2020 Junjiro R. Okajima
  */
 
 /*

fs/aufs/xattr.c

 // SPDX-License-Identifier: GPL-2.0
 /*
- * Copyright (C) 2014-2019 Junjiro R. Okajima
+ * Copyright (C) 2014-2020 Junjiro R. Okajima
  */
 
 /*

fs/aufs/xino.c

 // SPDX-License-Identifier: GPL-2.0
 /*
- * Copyright (C) 2005-2019 Junjiro R. Okajima
+ * Copyright (C) 2005-2020 Junjiro R. Okajima
  */
 
 /*

include/uapi/linux/aufs_type.h

 /* SPDX-License-Identifier: GPL-2.0 */
 /*
- * Copyright (C) 2005-2019 Junjiro R. Okajima
+ * Copyright (C) 2005-2020 Junjiro R. Okajima
  */
 
 #ifndef __AUFS_TYPE_H__