Move gn secondary_source to the build/ directory

tools/gn/secondary/testing/gmock/BUILD.gn

-# Copyright (c) 2013 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.
-
-config("gmock_config") {
-  # Gmock headers need to be able to find themselves.
-  include_dirs = [ "include" ]
-}
-
-static_library("gmock") {
-  sources = [
-    # Sources based on files in r173 of gmock.
-    "include/gmock/gmock-actions.h",
-    "include/gmock/gmock-cardinalities.h",
-    "include/gmock/gmock-generated-actions.h",
-    "include/gmock/gmock-generated-function-mockers.h",
-    "include/gmock/gmock-generated-matchers.h",
-    "include/gmock/gmock-generated-nice-strict.h",
-    "include/gmock/gmock-matchers.h",
-    "include/gmock/gmock-spec-builders.h",
-    "include/gmock/gmock.h",
-    "include/gmock/internal/gmock-generated-internal-utils.h",
-    "include/gmock/internal/gmock-internal-utils.h",
-    "include/gmock/internal/gmock-port.h",
-    #"src/gmock-all.cc",  # Not needed by our build.
-    "src/gmock-cardinalities.cc",
-    "src/gmock-internal-utils.cc",
-    "src/gmock-matchers.cc",
-    "src/gmock-spec-builders.cc",
-    "src/gmock.cc",
-  ]
-
-  # This project includes some stuff form gtest's guts.
-  include_dirs = [ "../gtest/include" ]
-
-  direct_dependent_configs = [
-    ":gmock_config",
-    "//testing/gtest:gtest_config",
-  ]
-}
-
-static_library("gmock_main") {
-  sources = [ "src/gmock_main.cc" ]
-  deps = [ ":gmock" ]
-}