alpha blend 4 pixel loop bug fix and blender C code match SSE for better testability and reference code for future optimized code.
BUG=none
TEST=none
Review URL: https://webrtc-codereview.appspot.com/645008

git-svn-id: http://libyuv.googlecode.com/svn/trunk@287 16f28f9a-4ce2-e073-06de-1de4eb20be90
5 files changed