Simplify //mojo/public/c/system targets

mojo/go/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/go/rules.gni")
 
 if (is_android) {
   group("go") {
     deps = [
       ":go_sample_app",
     ]
   }
   go_shared_library("go_sample_app") {
     sources = [
       "sample_app/app.go",
     ]
     deps = [
-      "//mojo/public/c/system:for_shared_library",
+      "//mojo/public/c/system",
+      "//mojo/public/platform/native:system",
     ]
   }
 } else if (is_linux) {
   group("go") {
     deps = [
       ":system_test",
     ]
   }
   go_test_binary("system_test") {
     sources = [
       "tests/system_test.go",
     ]
     static_library_sources = [
       "c_embedder/c_embedder.cc",
       "c_embedder/c_embedder.h",
     ]
     deps = [
       "//mojo/edk/system",
     ]
   }
 }