Make the outdated build detector disabler load and run on XP.

chrome/tools/disable_outdated_build_detector/BUILD.gn

 # Copyright (c) 2016 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("//chrome/version.gni")
 import("//testing/test.gni")
 
 if (is_win) {
+  config("xp") {
+    # Target low-end CPUs on XP.
+    cflags = [ "/arch:IA32" ]
+    defines = [
+      "NTDDI_VERSION=0x05010200",

[Reid Kleckner, 2016/08/20 15:30:45]

This define conflicts with the global one:
https://cs.chromium.org/chromium/src/build/config/win/BUILD.gn?q=NTDDI_VERSIO...

We're getting -Wmacro-redefined warnings on clang buildbots:
https://build.chromium.org/p/chromium.fyi/builders/CrWinAsan/builds/3989/step...

FAILED: obj/chrome/tools/disable_outdated_build_detector/lib/constants.obj
...
In file included from <built-in>:322:
<command line>(54,9):  error: 'NTDDI_VERSION' macro redefined
[-Werror,-Wmacro-redefined]
#define NTDDI_VERSION 0x05010200
        ^
<command line>(42,9):  note: previous definition is here
#define NTDDI_VERSION 0x0A000000
        ^

[grt (UTC plus 2), 2016/08/20 15:43:59]

I was afraid of that. There's no easy way around it, as the original definition
is in here:
https://cs.chromium.org/chromium/src/build/config/win/BUILD.gn?dr=C&q=runtime....

Can we live with it for a short time, or disable the warning on these targets?

+      "WINVER=0x0501",
+      "_WIN32_WINNT=0x0501",
+    ]
+  }
+
   executable("disable_outdated_build_detector") {
     sources = [
       "disable_outdated_build_detector_main.cc",
     ]
 
-    configs -= [ "//build/config/win:console" ]
-    configs += [ "//build/config/win:windowed" ]
+    configs -= [
+      "//build/config/win:console",
+      "//build/config/win:winver",
+    ]
+    configs += [
+      "//build/config/win:windowed",
+      ":xp",
+    ]
 
     deps = [
       ":disable_outdated_build_detector_exe_version",
       ":lib",
-      "//base",
       "//build/win:default_exe_manifest",
     ]
   }
 
   process_version("disable_outdated_build_detector_exe_version") {
     template_file = "disable_outdated_build_detector_exe_version.rc.version"
     output = "$target_gen_dir/disable_outdated_build_detector_exe_version.rc"
   }
 
   source_set("lib") {
     sources = [
       "constants.cc",
       "constants.h",
       "disable_outdated_build_detector.cc",
       "disable_outdated_build_detector.h",
       "google_update_integration.cc",
       "google_update_integration.h",
     ]
-
-    public_deps = [
-      "//base",
-    ]
+    configs -= [ "//build/config/win:winver" ]
+    configs += [ ":xp" ]
   }
 
   test("disable_outdated_build_detector_unittests") {
     sources = [
       "disable_outdated_build_detector_unittest.cc",
       "google_update_integration_unittest.cc",
       "run_all_unittests.cc",
     ]
 
     deps = [
       ":lib",
       "//base",
       "//base/test:test_support",
       "//chrome/installer/util:with_no_strings",
       "//testing/gmock",
       "//testing/gtest",
     ]
   }
 }