BUG=76
TEST=unittests for YUY2ToARGB and UYVYToARGB
Review URL: https://webrtc-codereview.appspot.com/763006

git-svn-id: http://libyuv.googlecode.com/svn/trunk@334 16f28f9a-4ce2-e073-06de-1de4eb20be90