Fixed handling of 6XX responses in sip_response_terminates_dialog().

Bug found by coverity.

darcs-hash:20051215121129-65a35-1050b57f135efdbcaf7736c48820f2a3d64dde69.gz

libsofia-sip-ua/sip/sip_util.c

@@ -1158,7 +1158,7 @@ int sip_response_terminates_dialog(int response_code,
     return 0;
   }
 
-  if (response_code < 600) switch (response_code) {
+  if (response_code < 700) switch (response_code) {
   case 600: /* 600 and 6xx unrecognized responses */
   default:
     /** @par 600 and 6xx unrecognized responses