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

examples/aura_demo/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("//mojo/public/mojo_application.gni")
 
 assert(use_aura)
 
 mojo_native_application("aura_demo") {
   sources = [
     "aura_demo.cc"
   ]
 
   deps = [
     "//base",
     "//cc",
     "//ui/aura",
     "//ui/base",
     "//ui/compositor",
     "//ui/gfx",
     "//ui/gfx/geometry",
     "//mojo/application",
     "//mojo/common",
     "//mojo/converters/geometry",
     "//mojo/aura",
-    "//mojo/public/c/system:for_shared_library",
     "//mojo/public/cpp/system",
     "//mojo/services/public/interfaces/geometry",
     "//mojo/services/public/interfaces/native_viewport",
     "//mojo/services/public/cpp/view_manager",
   ]
 
   datadeps = [ ":init" ]
 }
 
 mojo_native_application("init") {
   output_name = "aura_demo_init"
 
   sources = [
     "view_manager_init.cc",
   ]
 
   deps = [
     "//base",
     "//mojo/application",
-    "//mojo/public/c/system:for_shared_library",
     "//mojo/public/interfaces/application",
     "//mojo/services/public/cpp/view_manager",
     "//mojo/services/public/interfaces/view_manager",
   ]
 }