Adds support for a new target spec: 'mac_xcuitest_bundle'. This allows us to create UI testing bund…

test/mac/xcuitest/main.m

+// 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.
+
+#import <UIKit/UIKit.h>
+
+#import "MyAppDelegate.h"
+
+int main(int argc, char * argv[]) {
+  @autoreleasepool {
+    UIApplicationMain(argc, argv,
+                      nil, NSStringFromClass([MyAppDelegate class]));
+  }
+  return 1;
+}