BUG=388
TESTED=set LIBYUV_DISABLE_ASM=1 out\release\libyuv_unittest --gtest_catch_exceptions=0 --gtest_filter=*I420ToARGB_Opt
R=brucedawson@google.com, harryjin@google.com

Review URL: https://webrtc-codereview.appspot.com/35609004

git-svn-id: http://libyuv.googlecode.com/svn/trunk@1213 16f28f9a-4ce2-e073-06de-1de4eb20be90