coccinelle/null: solve parse error

This patch solves the parse-error by adding @@ . This is necessary since
Coccinelle version 1.0.0-rc20. Also, the comment is added to use a
recent version of Coccinelle.
Signed-off-by: Himangi Saraogi <himangi774@gmail.com>
Acked-by: Julia Lawall <julia.lawall@lip6.fr>
Signed-off-by: Michal Marek <mmarek@suse.cz>

scripts/coccinelle/null/badzero.cocci

@@ -10,7 +10,7 @@
 // Copyright: (C) 2012 Julia Lawall, INRIA/LIP6.  GPLv2.
 // Copyright: (C) 2012 Gilles Muller, INRIA/LiP6.  GPLv2.
 // URL: http://coccinelle.lip6.fr/
-// Comments:
+// Comments: Requires Coccinelle version 1.0.0-rc20 or later
 // Options:
 
 virtual patch
@@ -19,6 +19,7 @@ virtual org
 virtual report
 
 @initialize:ocaml@
+@@
 let negtable = Hashtbl.create 101
 
 @depends on patch@