Fix no-op builds, caused by an incorrect output in //sandbox/mac:generate_stubs.

sandbox/mac/sandbox_mac.gypi

 # 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': [
     {
       'target_name': 'sandbox',
       'type': '<(component)',
       'sources': [
@@ skipping 36 matching lines @@
           },
           'action_name': 'generate_stubs',
           'inputs': [
             '<(generate_stubs_script)',
             '<(generate_stubs_header_path)',
             '<(generate_stubs_sig_public_path)',
             '<(generate_stubs_sig_private_path)',
           ],
           'outputs': [
             '<(INTERMEDIATE_DIR)/<(generate_stubs_output_stem).cc',
-            '<(INTERMEDIATE_DIR)/<(generate_stubs_project)/<(generate_stubs_output_stem).h',
+            '<(SHARED_INTERMEDIATE_DIR)/<(generate_stubs_project)/<(generate_stubs_output_stem).h',
           ],
           'action': [
             'python',
             '<(generate_stubs_script)',
             '-i', '<(INTERMEDIATE_DIR)',
             '-o', '<(SHARED_INTERMEDIATE_DIR)/<(generate_stubs_project)',
             '-t', 'posix_stubs',
             '-e', '<(generate_stubs_header_path)',
             '-s', '<(generate_stubs_output_stem)',
             '-p', '<(generate_stubs_project)',
@@ skipping 23 matching lines @@
       ],
       'link_settings': {
         'libraries': [
           '$(SDKROOT)/System/Library/Frameworks/CoreFoundation.framework',
           '$(SDKROOT)/System/Library/Frameworks/Foundation.framework',
         ],
       },
     },
   ],
 }