proc_cloning: Fix specialising a function at the same parameter position more than once.

The same name was used multiple times, because the counter was not increased anymore.
This was broken more than 6 years ago in 9d564d61.
This fixes opt/proc_cloning003.c.

ir/opt/proc_cloning.c

@@ -429,7 +429,7 @@ static ir_entity *clone_method(const quadruple_t *q)
 	static size_t nr = 0;
 
 	/* We get a new ident for our clone method.*/
-	ident     *const clone_ident = get_clone_ident(get_entity_ident(q->ent), q->pos, nr);
+	ident     *const clone_ident = get_clone_ident(get_entity_ident(q->ent), q->pos, nr++);
 	/* We get our entity for the clone method. */
 	ir_type   *const owner       = get_entity_owner(q->ent);
 	ir_entity *const new_entity  = clone_entity(q->ent, clone_ident, owner);