remove row table, make C use math that mimics SIMD for exactness.  Also 2x faster than old code which mimiced old SIMD via tables.  9000 ms instead of 20000 ms
BUG=none
TEST=none
Review URL: http://webrtc-codereview.appspot.com/267020

git-svn-id: http://libyuv.googlecode.com/svn/trunk@85 16f28f9a-4ce2-e073-06de-1de4eb20be90