Simplify the thunk targets since we don't support apps as components

mojo/tools/package_manager/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("//mojo/public/mojo_application.gni")
 
 mojo_native_application("package_manager") {
   output_name = "mojo_package_manager"
 
   sources = [
     "manifest.cc",
     "manifest.h",
     "package_fetcher.cc",
     "package_fetcher.h",
     "package_manager.cc",
     "package_manager_application.cc",
     "package_manager_application.h",
     "unpacker.cc",
     "unpacker.h",
   ]
 
   deps = [
     "//base",
     "//mojo/application",
     "//mojo/common",
-    "//mojo/public/c/system:for_shared_library",
     "//mojo/public/cpp/system",
     "//mojo/public/cpp/utility",
     "//mojo/services/public/interfaces/network",
     "//third_party/zlib:zip",
     "//url",
   ]
 }