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

third_party/qcms/BUILD.gn

Index: third_party/qcms/BUILD.gn
diff --git a/third_party/qcms/BUILD.gn b/third_party/qcms/BUILD.gn
index b0593192f536e5f87533c5c6468417103dc22199..ee62b8e7f55f9c46a8cdc3d5a8a390c2a571d713 100644
--- a/third_party/qcms/BUILD.gn
+++ b/third_party/qcms/BUILD.gn
@@ -25,10 +25,10 @@ source_set("qcms") {
   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" ]