remove unused function ScalePlaneBoxRow_* which was for slow box filter that is no longer used. BUG=432 TESTED=try bots R=bcornell@google.com
remove unused function ScalePlaneBoxRow_* which was for slow box filter that is no longer used.
BUG=432
TESTED=try bots
R=bcornell@google.com

Review URL: https://webrtc-codereview.appspot.com/51779004
Vairn/libyuv,sathishkumars3/libyuv,sathishkumars3/libyuv,RockySteveJobs/libyuv,uditkumawat/libyuv,Vairn/libyuv,chucvv/libyuv,RockySteveJobs/libyuv,Vairn/libyuv,gigakuma/libyuv,RockySteveJobs/libyuv,dexcz/libyuv,chucvv/libyuv,hyper123/libyuv,yzhikan/libyuv,chucvv/libyuv,sathishkumars3/libyuv,mosterta/libyuv,uditkumawat/libyuv,yzhikan/libyuv,yzhikan/libyuv,mosterta/libyuv,hyper123/libyuv,gigakuma/libyuv,dexcz/libyuv,hyper123/libyuv,gigakuma/libyuv,uditkumawat/libyuv,mosterta/libyuv,dexcz/libyuv