Move the mini_installer_version rule to its own gyp file.

chrome/installer/mini_installer_syzygy.gyp

 # Copyright (c) 2011 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.
 {
   'variables': {
-    'version_py': '<(DEPTH)/build/util/version.py',
-    'version_path': '<(DEPTH)/chrome/VERSION',
-    'lastchange_path': '<(DEPTH)/build/util/LASTCHANGE',
-    'branding_dir': '../app/theme/<(branding_path_component)',
     'msvs_use_common_release': 0,
     'msvs_use_common_linker_extras': 0,
   },
   'includes': [
     '../../build/win_precompile.gypi',
   ],
   'conditions': [
     # This target won't build in fastbuild, since there are no PDBs.
     ['OS=="win" and fastbuild==0', {
       'conditions': [
@@ skipping 37 matching lines @@
               'includes': [ 'mini_installer.gypi', ],
             },
           ],
         }],
       ],
     },{
       'targets': [],
     }],
   ],
 }