Change name of variable for convert to crop_width/height instead of dst_width/height to clarify that it is used to crop the original before rotation and is not the final destination size.
BUG=none
TESTED=local builds still work
R=wjia@google.com, wjia@webrtc.org

Review URL: https://webrtc-codereview.appspot.com/5859004

git-svn-id: http://libyuv.googlecode.com/svn/trunk@915 16f28f9a-4ce2-e073-06de-1de4eb20be90