Build libyuv w/ no_chromium_code in GN.

This disables a couple of windows warnings that will otherwise
fire on Win64, causing compile failures.

BUG=432375
suppress size_t -> int warnings

R=harryjin@google.com

Review URL: https://webrtc-codereview.appspot.com/24299004

git-svn-id: http://libyuv.googlecode.com/svn/trunk@1171 16f28f9a-4ce2-e073-06de-1de4eb20be90

BUILD.gn

@@ -69,6 +69,9 @@ source_set("libyuv") {
     "source/video_common.cc",
   ]
 
+  configs -= [ "//build/config/compiler:chromium_code" ]
+  configs += [ "//build/config/compiler:no_chromium_code" ]
+
   public_configs = [ ":libyuv_config" ]
 
   defines = []