ans: Switch from uABS to rABS

This is in preparation for expanding the state range.

No discernible compression impact

ans_multioff@2017-01-25T20:58:18.756Z -> ans_multioff_rabs@2017-01-26T01:05:12.801Z

     PSNR | PSNR Cb | PSNR Cr | PSNR HVS |    SSIM | MS SSIM | CIEDE 2000
  -0.0001 | -0.0001 | -0.0001 |  -0.0001 | -0.0001 | -0.0001 | -0.0001

https://arewecompressedyet.com/?job=ans_multioff%402017-01-25T20%3A58%3A18.756Z&job=ans_multioff_rabs%402017-01-26T01%3A05%3A12.801Z

Change-Id: Ie1817991190f1de6d9c31e0c97f77efbd5869d35
7 files changed