Move cygwin_dir to common.gypi.

dart/tools/gyp/common.gypi

Index: dart/tools/gyp/common.gypi
diff --git a/dart/tools/gyp/common.gypi b/dart/tools/gyp/common.gypi
index 3577f922002e7fa359dbd34e9ffa49a56e1c0f6d..cfbfcd080b8f16c7d11301b96d9803b67bcda505 100644
--- a/dart/tools/gyp/common.gypi
+++ b/dart/tools/gyp/common.gypi
@@ -1,10 +1,13 @@
-# Copyright (c) 2011, the Dart project authors.  Please see the AUTHORS file
+# Copyright (c) 2012, the Dart project authors.  Please see the AUTHORS file
 # for details. All rights reserved. Use of this source code is governed by a
 # BSD-style license that can be found in the LICENSE file.
 
 # A set of variables needed to build some of the Chrome based subparts of the
 # Dash project (e.g. V8). This is in no way a complete list of variables being
 # defined by Chrome, but just the minimally needed subset.
+
+# Note: this file is similar to all.gypi, but is used when running gyp
+# from subproject directories.  This is deprecated, but still supported.
 {
   'variables': {
     'library': 'static_library',
@@ -19,6 +22,11 @@
         'ldflags': [ '-pthread', ],
       },
     }],
+    [ 'OS=="win"', {
+      'target_defaults': {
+        'msvs_cygwin_dirs': ['<(DEPTH)/../third_party/cygwin'],
+      },
+    }],
   ],
   'includes': [
     'xcode.gypi',