Fix selection of bitcost for NxN mode intra CUs.
Fix selection of bitcost for NxN mode intra CUs.

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