BUG=344
TESTED=libyuv_unittest --gtest_filter=*CropNV12
R=tpsiaki@google.com

Review URL: https://webrtc-codereview.appspot.com/16939004

git-svn-id: http://libyuv.googlecode.com/svn/trunk@1036 16f28f9a-4ce2-e073-06de-1de4eb20be90