Switching cygwin setup_mount project to use bare command line....

build/win/system.gyp

 # Copyright (c) 2009 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.
 
 {
   'includes': [
     '../common.gypi',
   ],
   'targets': [
     {
       'target_name': 'cygwin',
       'type': 'none',
       'actions': [
         {
           'action_name': 'setup_mount',
+          'msvs_cygwin_shell': 0,
           'inputs': [
             '../../third_party/cygwin/setup_mount.bat',
           ],
           # Visual Studio requires an output file, or else the
           # custom build step won't run.
           'outputs': [
             '../../third_party/cygwin/_always_run_setup_mount.marker',
           ],
           'action': ['<@(_inputs)'],
         },
       ],
     },
   ],
 }