Convert some GN test support targets to static libs.

ppapi/shared_impl/BUILD.gn

 # Copyright 2015 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/nacl/config.gni")
 
 component("shared_impl") {
   output_name = "ppapi_shared"
 
   sources = [
@@ skipping 181 matching lines @@
       "//third_party/icu:icuuc",
       "//url",
     ]
   }
 
   if (is_mac) {
     libs = [ "QuartzCore.framework" ]
   }
 }
 
-source_set("test_support") {
+static_library("test_support") {
   testonly = true
 
   sources = [
     "test_globals.cc",
     "test_globals.h",
     "test_utils.cc",
     "test_utils.h",
   ]
 
   public_deps = [
     "//ppapi/shared_impl",
   ]
   deps = [
     "//base/test:test_support",
     "//ipc",
     "//ipc:test_support",
     "//ppapi/proxy",
     "//testing/gmock",
     "//testing/gtest",
   ]
 }