libvpx: Update dependencies of generated asm offsets.

unpack_lib_posix.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.
 
 # This action takes an archive (.a) file and unpacks it unto object (.o) files.
 # The following input gyp variables are required:
 #   unpack_lib, the library to unpack.
 #   object_file_output_dir, the output directory of extracted object file.
 #   object_file_to_extract, the object file to be extracted.
 #   unpack_lib_search_path_list, a list of paths to search for the library.
@@ skipping 21 matching lines @@
       'variables' : {
         'ar_cmd': [],
               'conditions': [
           ['android_webview_build==1', {
             'ar_cmd': ['-r', '$(abspath $($(gyp_var_prefix)TARGET_AR))'],
           }],
         ],
       },
       'action_name': 'unpack_lib_posix',
       'inputs': [
+        'unpack_lib_posix.sh',
         '<(unpack_lib)',
       ],
       'outputs': [
         '<(object_file_output_dir)/<(object_file_to_extract)',
       ],
       'action': [
         '<(DEPTH)/third_party/libvpx/unpack_lib_posix.sh',
         '-d', '<(object_file_output_dir)',
         '-f', '<(object_file_to_extract)',
         '<@(unpack_lib_search_path_list)',
         '<@(ar_cmd)',
       ],
       'process_output_as_sources': 1,
     },
   ],
 }