BUG=264
TEST=ARGBInterpolate*
R=changjun.yang@intel.com

Review URL: https://webrtc-codereview.appspot.com/2160004

git-svn-id: http://libyuv.googlecode.com/svn/trunk@777 16f28f9a-4ce2-e073-06de-1de4eb20be90