run cygwin mount setup in runhooks, and remove some references to it

chrome/chrome_installer.gypi

 # Copyright (c) 2012 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': {
     'lastchange_path': '<(SHARED_INTERMEDIATE_DIR)/build/LASTCHANGE',
     # 'branding_dir' is set in the 'conditions' section at the bottom.
   },
   'conditions': [
@@ skipping 196 matching lines @@
         {
           'target_name': 'setup',
           'type': 'executable',
           'dependencies': [
             'installer_util',
             'installer_util_strings',
             '<(DEPTH)/base/base.gyp:base',
             '<(DEPTH)/build/temp_gyp/googleurl.gyp:googleurl',
             '<(DEPTH)/build/util/build_util.gyp:lastchange#target',
             '<(DEPTH)/build/util/support/support.gyp:*',
-            '<(DEPTH)/build/win/system.gyp:cygwin',
             '<(DEPTH)/chrome_frame/chrome_frame.gyp:chrome_tab_idl',
             '<(DEPTH)/chrome_frame/chrome_frame.gyp:npchrome_frame',
             '<(DEPTH)/breakpad/breakpad.gyp:breakpad_handler',
             '<(DEPTH)/rlz/rlz.gyp:rlz_lib',
             '<(DEPTH)/third_party/zlib/zlib.gyp:zlib',
           ],
           'include_dirs': [
             '<(DEPTH)',
             '<(INTERMEDIATE_DIR)',
             '<(SHARED_INTERMEDIATE_DIR)/setup',
@@ skipping 708 matching lines @@
       'variables': {
          'branding_dir': 'app/theme/google_chrome',
       },
     }, { # else branding!="Chrome"
       'variables': {
          'branding_dir': 'app/theme/chromium',
       },
     }],
   ],
 }