Mark the intl file-reading tests slow on debug mips

pkg/intl/test/date_time_format_file_even_test.dart

 // Copyright (c) 2012, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
 // BSD-style license that can be found in the LICENSE file.
 
 /**
  * Tests date formatting and parsing using locale data read from the
  * local file system. This tests one half the locales, since testing all
  * of them takes long enough that it may cause timeouts in the test bots.
  */
 
 library date_time_format_file_test_2;
 import 'date_time_format_test_stub.dart';
 import 'data_directory.dart';
 import 'package:intl/date_symbol_data_file.dart';
+import 'package:unittest/unittest.dart';
 
 main() {
+  unittestConfiguration.timeout = new Duration(seconds: 60);
   runWith(evenLocales, dataDirectory, initializeDateFormatting);
 }