Fix bug that causes lambda_cost to be ignored in search_best_mode.
Fix bug that causes lambda_cost to be ignored in search_best_mode.

lu-zero/kvazaar,ultravideo/kvazaar,lu-zero/kvazaar,lu-zero/kvazaar,ultravideo/kvazaar,ultravideo/kvazaar,lu-zero/kvazaar,ultravideo/kvazaar,ultravideo/kvazaar