Use round-to-even for BMA MC predictors to avoid biasing
Use round-to-even for BMA MC predictors to avoid biasing

Results on video-1-short:
           RATE (%)  DSNR (dB)
    PSNR -0.05573  0.00298
 PSNRHVS -0.06775  0.00537
    SSIM -0.05525  0.00266
FASTSSIM -0.06724  0.00412

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