Optimization for HBD filter intra predictors (SSE4.1)

- Add unit tests to verify the bit-exact.
- Speed unit test, function improvement: about 8%-23%.
- On E5-2680, park_joy_1080p_12, 25 frames, --kf-max-dist=1
  encoding time improves from <1% to 3.5%

Change-Id: Ic16368885bb253db0200c3a6db143ab1a0b7fc26