Add new NS error type, null and related tokens.

includes/dhctoken.h

@@ -214,7 +214,23 @@ enum dhcp_token {
 	NO = 431,
 	TOKEN_DELETE,
 	NS_UPDATE,
-	UPDATE
+	UPDATE,
+	SWITCH,
+	CASE,
+	NS_FORMERR,
+	NS_NOERROR,
+	NS_NOTAUTH,
+	NS_NOTIMP,
+	NS_NOTZONE,
+	NS_NXDOMAIN,
+	NS_NXRRSET,
+	NS_REFUSED,
+	NS_SERVFAIL,
+	NS_YXDOMAIN,
+	NS_YXRRSET,
+	TOKEN_NULL,
+	TOKEN_SET,
+	DEFINED
 };
 
 #define is_identifier(x)	((x) >= FIRST_TOKEN &&	\