This bug made the rd loop use one-side obmc (compound of the current
predictor and the predictors of the left mi's, while the above ones
are ignored by mistake) to determine whether to use obmc. This fix
improved the compression performance by ~0.6% on different test sets.

Coding gain (%) of obmc experiment on derflr/derfhd/hevcmr/hevchd:
1.568/TBD/1.628/TBD

Change-Id: I43b239bedf9a8eebfd02315b1b036e140a998140