Update Chomium's build files to work w/ latest GN binaries.

third_party/qcms/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.
 
 config("qcms_config") {
   include_dirs = [ "src" ]
 }
 
 source_set("qcms") {
   sources = [
     "src/chain.c",
     "src/chain.h",
     "src/iccread.c",
     "src/matrix.c",
     "src/matrix.h",
     "src/qcms.h",
     "src/qcmsint.h",
     "src/qcmstypes.h",
     "src/transform.c",
     "src/transform_util.c",
     "src/transform_util.h",
   ]
 
   configs -= [ "//build/config/compiler:chromium_code" ]
   configs += [ "//build/config/compiler:no_chromium_code" ]
   public_configs = [ ":qcms_config" ]
 
-  if (cpu_arch == "x86" || cpu_arch == "x64") {
+  if (current_cpu == "x86" || current_cpu == "x64") {
     defines = [ "SSE2_ENABLE" ]
     sources += [ "src/transform-sse2.c" ]
-    if (!(is_win && cpu_arch == "x64")) {
+    if (!(is_win && current_cpu == "x64")) {
       # QCMS assumes this target isn't compiled since MSVC x64 doesn't support
       # the MMX intrinsics present in the SSE1 code.
       sources += [ "src/transform-sse1.c" ]
     }
   }
 
   if (is_win) {
     cflags = [
       "/wd4056",  # Overflow in floating-point constant arithmetic (INFINITY).
       "/wd4756",  # Overflow in constant arithmetic (INFINITY).
     ]
   }
 }