ninja/mac: Let copies sections that copy stuff inside a bundle mark the bundle as dirty.

test/mac/postbuild-copy-bundle/test.gyp

 # Copyright (c) 2012 Google Inc. All rights reserved.
 # Use of this source code is governed by a BSD-style license that can be
 # found in the LICENSE file.
 {
   'targets': [
     {
       'target_name': 'test_bundle',
       'product_name': 'My Framework',
       'type': 'shared_library',
       'mac_bundle': 1,
       'sources': [ 'empty.c', ],
       'xcode_settings': {
         'INFOPLIST_FILE': 'Framework-Info.plist',
       },
       'mac_bundle_resources': [
         'resource_file.sb',
       ],
+      'copies': [
+        {
+          'destination': '<(PRODUCT_DIR)/$(CONTENTS_FOLDER_PATH)/Libraries',
+          'files': [ 'copied.txt' ],
+        },
+      ],
     },
     {
       'target_name': 'test_app',
       'product_name': 'Test App',
       'type': 'executable',
       'mac_bundle': 1,
       'dependencies': [
         'test_bundle',
       ],
       'sources': [ 'main.c', ],
       'xcode_settings': {
         'INFOPLIST_FILE': 'TestApp-Info.plist',
       },
       'postbuilds': [
         {
           'postbuild_name': 'Copy dependent framework into app',
           'action': [
             './postbuild-copy-framework.sh',
             '${BUILT_PRODUCTS_DIR}/My Framework.framework',
             '${BUILT_PRODUCTS_DIR}/${CONTENTS_FOLDER_PATH}/',
           ],
         },
       ],
     },
   ],
 }