Add missing 'hard_dependency' in gyp targets using grit_action

extensions/extensions_strings.gyp

 # Copyright 2014 The Chromium Authors. All rights reserved.
 # Use of this source code is governed by a BSD-style license that can be
 # found in the LICENSE file.
 
 {
   'targets': [
     {
       # GN version: //extensions:strings
       'target_name': 'extensions_strings',
       'type': 'none',
+      'hard_dependency': 1,
       'variables': {
         'grit_out_dir': '<(SHARED_INTERMEDIATE_DIR)/extensions/strings',
       },
       'actions': [
         {
           'action_name': 'generate_extensions_strings',
           'variables': {
             'grit_grd_file': 'extensions_strings.grd',
           },
           'includes': [ '../build/grit_action.gypi' ],
         },
       ],
       'includes': [ '../build/grit_target.gypi' ],
     },
   ],
 }