Remove alignment from ARGBToRGB24 and ARGBToRAW to allow fast code to be used all of the time.  Improves performance on Westmere and beyond, hurts performance for aligned buffers on older CPUs.
BUG=230
TESTED=try bot
R=nfullagar@google.com

Review URL: https://webrtc-codereview.appspot.com/2197007

git-svn-id: http://libyuv.googlecode.com/svn/trunk@785 16f28f9a-4ce2-e073-06de-1de4eb20be90