GN: Replace mojo/system.gni with forwarding groups

mojo/services/public/cpp/surfaces/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/system.gni")
-
 # GYP version: mojo/mojo_services.gypi:mojo_surfaces_lib
 component("surfaces") {
   output_name = "mojo_surfaces_lib"
 
   deps = [
     "//base",
     "//cc",
     "//cc/surfaces",
     "//ui/gfx",
     "//ui/gfx/geometry",
     "//mojo/environment:chromium",
+    "//mojo/public/c/system:for_component",
     "//mojo/services/public/interfaces/surfaces",
     "//mojo/services/public/cpp/geometry",
-  ] + mojo_system_for_component
+  ]
 
   forward_dependent_configs_from = [
     "//mojo/services/public/cpp/geometry",
     "//ui/gfx",
   ]
 
   defines = [
     "MOJO_SURFACES_IMPLEMENTATION",
   ]
 
   sources = [
     "lib/surfaces_type_converters.cc",
     "lib/surfaces_utils.cc",
     "mojo_surfaces_export.h",
     "surfaces_type_converters.h",
     "surfaces_utils.h",
   ]
 }