Adds generator support for Xcode 5 xctest targets.

test/mac/xctest/Shared/shared.gyp

Index: test/mac/xctest/Shared/shared.gyp
diff --git a/test/mac/xctest/Shared/shared.gyp b/test/mac/xctest/Shared/shared.gyp
new file mode 100644
index 0000000000000000000000000000000000000000..83e4a30a69d33e7577d542fcf3b46abf83847517
--- /dev/null
+++ b/test/mac/xctest/Shared/shared.gyp
@@ -0,0 +1,21 @@
+# Copyright (c) 2013 Google Inc. All rights reserved.
+# Use of this source code is governed by a BSD-style license that can be
+# found in the LICENSE file.
+{
+  'targets': [
+    {
+      'target_name': 'shared',
+      'type': 'static_library',
+      'sources': [
+        'Shared.h',
+        'Shared.m',
+      ],
+      'direct_dependent_settings': {
+        'include_dirs': [ '.' ],
+      },
+      'xcode_settings': {
+        'GCC_SYMBOLS_PRIVATE_EXTERN': 'NO',
+      },
+    },
+  ],
+}