Alpha's biggest fraction is 1/8, so Q3 does not change the bitstream.

Results on Subset1 (compared to 503aca74 with CfL enabled)

  PSNR | PSNR Cb | PSNR Cr | PSNR HVS |   SSIM | MS SSIM | CIEDE 2000
0.0000 |  0.0000 |  0.0000 |   0.0000 | 0.0000 |  0.0000 |     0.0000

Change-Id: I1fe5b2ace97179d5f950d7406a4f3d391924f89d