fix zigzag for computing nonzero count for 8x8 macroblocks. 8x8-inter still failing.
fix zigzag for computing nonzero count for 8x8 macroblocks. 8x8-inter still failing.

danielrh/losslessh264,danielrh/losslessh264,danielrh/losslessh264,danielrh/losslessh264,danielrh/losslessh264,danielrh/losslessh264,danielrh/losslessh264