Fix declaration of mu_sieve_vlist_do in libmu_sieve.

@@ -187,7 +187,7 @@ int mu_sieve_match_part_checker (const char *name, mu_list_t tags,
 				 mu_list_t args);
 /* Operations in value lists */
 mu_sieve_value_t *mu_sieve_value_get (mu_list_t vlist, size_t index);
-int mu_sieve_vlist_do (mu_sieve_value_t * val, mu_list_action_t * ac,
+int mu_sieve_vlist_do (mu_sieve_value_t * val, mu_list_action_t ac,
 		       void *data);
 int mu_sieve_vlist_compare (mu_sieve_value_t * a, mu_sieve_value_t * b,
 			    mu_sieve_comparator_t comp,

@@ -419,7 +419,7 @@ mu_sieve_tag_lookup (mu_list_t taglist, char *name, mu_sieve_value_t **arg)
 }
 
 int
-mu_sieve_vlist_do (mu_sieve_value_t *val, mu_list_action_t *ac, void *data)
+mu_sieve_vlist_do (mu_sieve_value_t *val, mu_list_action_t ac, void *data)
 {
   switch (val->type)
     {
@@ -428,7 +428,7 @@ mu_sieve_vlist_do (mu_sieve_value_t *val, mu_list_action_t *ac, void *data)
       return mu_list_foreach (val->v.list, ac, data);
       
     default:
-      return -1;
+      return EINVAL;
     }
 }