Change interface for enumerator_create_filter() callback

This avoids the unportable 5 pointer hack, but requires enumerating in
the callback.

src/pki/commands/signcrl.c

@@ -61,16 +61,24 @@ static void revoked_destroy(revoked_t *revoked)
 	free(revoked);
 }
 
-/**
- * Filter for revoked enumerator
- */
-static bool filter(void *data, revoked_t **revoked, chunk_t *serial, void *p2,
-				   time_t *date, void *p3, crl_reason_t *reason)
+CALLBACK(filter, bool,
+	void *data, enumerator_t *orig, va_list args)
 {
-	*serial = (*revoked)->serial;
-	*date = (*revoked)->date;
-	*reason = (*revoked)->reason;
-	return TRUE;
+	revoked_t *revoked;
+	crl_reason_t *reason;
+	chunk_t *serial;
+	time_t *date;
+
+	VA_ARGS_VGET(args, serial, date, reason);
+
+	if (orig->enumerate(orig, &revoked))
+	{
+		*serial = revoked->serial;
+		*date = revoked->date;
+		*reason = revoked->reason;
+		return TRUE;
+	}
+	return FALSE;
 }
 
 /**
@@ -392,7 +400,7 @@ static int sign_crl()
 	chunk_increment(crl_serial);
 
 	enumerator = enumerator_create_filter(list->create_enumerator(list),
-										  (void*)filter, NULL, NULL);
+										  filter, NULL, NULL);
 	crl = lib->creds->create(lib->creds, CRED_CERTIFICATE, CERT_X509_CRL,
 			BUILD_SIGNING_KEY, private, BUILD_SIGNING_CERT, ca,
 			BUILD_SERIAL, crl_serial,