Don't build sky_packager on Mac hosts

sky/BUILD.gn

 # Copyright 2014 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.
 
 import("//build/config/ui.gni")
 import("//tools/grit/grit_rule.gni")
 
 group("sky") {
   testonly = true
 
   deps = [
     "//services/debugger",
     "//sky/engine/platform:platform_unittests",
     "//sky/engine/web:sky_unittests",
     "//sky/engine/wtf:unittests",
     "//sky/tools/imagediff",
-    "//sky/tools/packager($host_toolchain)",
     "//sky/tools/tester",
     "//sky/viewer",
     ":sky_apk",
   ]
 
+  # Mac's host toolchain doesn't support C++11 and can't build the packager.
+  if (host_os != "mac") {
+    deps += [ "//sky/tools/packager($host_toolchain)" ]
+  }
+
   if (is_android) {
     deps += [ "//sky/apk/stocks" ]
   }
 
   if (!is_android) {
     deps += [ "//third_party/mesa:osmesa" ]
   }
 }
 
 group("sky_apk") {
   testonly = true
 
   deps = [
     "//mojo/dart/mojo_services",
     "//mojo/dart/mojom",
     "//mojo/public/dart:mojo",
     "//sky/sdk",
     "//third_party/dart-pkg",
   ]
 
   if (is_android) {
     deps += [
       "//sky/apk/demo",
       "//sky/services/intents",
     ]
   }
 }