Remove build references to third_party/cygwin

build/common.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.
 
 # IMPORTANT:
 # Please don't directly include this file if you are building via gyp_chromium,
 # since gyp_chromium is automatically forcing its inclusion.
 {
   # Variables expected to be overriden on the GYP command line (-D) or by
   # ~/.gyp/include.gypi.
@@ skipping 4537 matching lines @@
               }],
             ],
           }],
         ],
         'msvs_system_include_dirs': [
           '<(windows_sdk_path)/Include/shared',
           '<(windows_sdk_path)/Include/um',
           '<(windows_sdk_path)/Include/winrt',
           '$(VSInstallDir)/VC/atlmfc/include',
         ],
-        'msvs_cygwin_dirs': ['<(DEPTH)/third_party/cygwin'],
         'msvs_cygwin_shell': 0,
         'msvs_disabled_warnings': [4351, 4355, 4396, 4503, 4819,
           # TODO(maruel): These warnings are level 4. They will be slowly
           # removed as code is fixed.
           4100, 4121, 4125, 4127, 4130, 4131, 4189, 4201, 4238, 4244, 4245,
           4310, 4428, 4481, 4505, 4510, 4512, 4530, 4610, 4611, 4701, 4702,
           4706,
         ],
         'msvs_settings': {
           'VCCLCompilerTool': {
@@ skipping 311 matching lines @@
     # settings in target dicts.  SYMROOT is a special case, because many other
     # Xcode variables depend on it, including variables such as
     # PROJECT_DERIVED_FILE_DIR.  When a source group corresponding to something
     # like PROJECT_DERIVED_FILE_DIR is added to a project, in order for the
     # files to appear (when present) in the UI as actual files and not red
     # red "missing file" proxies, the correct path to PROJECT_DERIVED_FILE_DIR,
     # and therefore SYMROOT, needs to be set at the project level.
     'SYMROOT': '<(DEPTH)/xcodebuild',
   },
 }