Add support for 32-bit and 64-bit Windows compiles in GN.

build/config/compiler/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.
 
 # Base compiler configuration.
 config("compiler") {
   include_dirs = [ "//", root_gen_dir ]
   if (is_win) {
     cflags = [
       "/Gy",  # Enable function-level linking.
@@ skipping 65 matching lines @@
     # ------------------------------------
     if (is_linux) {
       cflags += [
         "-fPIC",
         "-pthread",
         "-pipe",  # Use pipes for communicating between sub-processes. Faster.
       ]
 
       # Use gold for linking on 64-bit Linux only (on 32-bit it runs out of
       # address space, and it doesn't support cross-compiling).
-      if (cpu_arch == "ia64") {
+      if (cpu_arch == "x64") {
         gold_path = rebase_path("//third_party/gold", ".", root_build_dir)
         ldflags += [
           "-B$gold_path",
 
           # There seems to be a conflict of --icf and -pie in gold which can
           # generate crashy binaries. As a security measure, -pie takes
           # precendence for now.
           # TODO(brettw) common.gypi has this only for target toolset.
           #"-Wl,--icf=safe",
           "-Wl,--icf=none",
@@ skipping 290 matching lines @@
   } else {
     cflags = [ "-g1" ]
   }
 }
 
 config("no_symbols") {
   if (!is_win) {
     cflags = [ "-g0" ]
   }
 }