backend: non-functional code-fiddling: format codablock.c (clang-format

+ manual); add SPDX to all files; prefix include guards with Z_;
  move vim comment to bottom; remove some trailing spaces

backend/code16k.c

@@ -1,8 +1,7 @@
 /* code16k.c - Handles Code 16k stacked symbology */
-
 /*
     libzint - the open source barcode library
-    Copyright (C) 2008 - 2021 Robin Stuart <rstuart114@gmail.com>
+    Copyright (C) 2008-2022 Robin Stuart <rstuart114@gmail.com>
 
     Redistribution and use in source and binary forms, with or without
     modification, are permitted provided that the following conditions
@@ -29,16 +28,16 @@
     OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
     SUCH DAMAGE.
  */
-/* vim: set ts=4 sw=4 et : */
+/* SPDX-License-Identifier: BSD-3-Clause */
 
 /* Updated to comply with BS EN 12323:2005 */
 
 /* Code 16k can hold up to 77 characters or 154 numbers */
 
-#include <stdio.h>
-#include <assert.h>
 #include "common.h"
 #include "code128.h"
+#include <assert.h>
+#include <stdio.h>
 
 /* Note using C128Table with extra entry at 106 (Triple Shift) for C16KTable */
 
@@ -413,3 +412,5 @@ INTERNAL int code16k(struct zint_symbol *symbol, unsigned char source[], int len
 
     return error_number;
 }
+
+/* vim: set ts=4 sw=4 et : */