Convert some GN test support targets to static libs.

dbus/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/features.gni")
 import("//testing/test.gni")
 import("//third_party/protobuf/proto_library.gni")
 
 assert(use_dbus)
 
@@ skipping 41 matching lines @@
 }
 
 proto_library("test_proto") {
   sources = [
     "test_proto.proto",
   ]
 }
 
 # This target contains mocks that can be used to write unit tests without
 # issuing actual D-Bus calls.
-source_set("test_support") {
+static_library("test_support") {
   testonly = true
   sources = [
     "mock_bus.cc",
     "mock_bus.h",
     "mock_exported_object.cc",
     "mock_exported_object.h",
     "mock_object_manager.cc",
     "mock_object_manager.h",
     "mock_object_proxy.cc",
     "mock_object_proxy.h",
@@ skipping 52 matching lines @@
 
   deps = [
     ":dbus",
     "//base",
     "//base/test:test_support",
     "//build/config/sanitizers:deps",
   ]
 
   configs += [ "//build/config/linux/dbus" ]
 }