scripts: coccinelle: check for redeclaration

Avoid reporting on the use of an iterator index variable when
the variable is redeclared.
Signed-off-by: NJulia Lawall <Julia.Lawall@lip6.fr>
Signed-off-by: NMasahiro Yamada <yamada.masahiro@socionext.com>

scripts/coccinelle/iterators/use_after_iter.cocci

@@ -35,6 +35,7 @@ iterator name hlist_for_each_entry_from;
 iterator name hlist_for_each_entry_safe;
 statement S;
 position p1,p2;
+type T;
 @@
 
 (
@@ -125,6 +126,8 @@ sizeof(<+...c...+>)
 |
  &c->member
 |
+T c;
+|
 c = E
 |
 *c@p2