Tune activity masking QM for 32x32 and 64x64
Tune activity masking QM for 32x32 and 64x64

Hand tuned by fixing block size and toggling activity masking with the goal of
minimizing the difference in bitrate for each band.

ntt-short-1:
          LOW (%)  MEDIUM (%) HIGH (%)
    PSNR 0.126975 -0.053934 0.361041
 PSNRHVS -0.106454 -0.238131 -0.083673
    SSIM -0.251859 0.564909 0.183929
FASTSSIM -2.056769 -3.544245 -1.402435

Signed-off-by: Jean-Marc Valin <b20cab4bda6e09296359e6832b28734b973923d8@jmvalin.ca>

luctrudeau/daala,xiph/daala,luctrudeau/daala,xiph/daala,HeadhunterXamd/daala,jmvalin/daala,jmvalin/daala,ycho/daala,ycho/daala,xiphmont/daala,xiphmont/daala,xiph/daala,HeadhunterXamd/daala,luctrudeau/daala,jmvalin/daala,xiphmont/daala,xiph/daala,HeadhunterXamd/daala,luctrudeau/daala,luctrudeau/daala,jmvalin/daala,xiphmont/daala,xiph/daala,ycho/daala,HeadhunterXamd/daala,ycho/daala,jmvalin/daala,HeadhunterXamd/daala,xiphmont/daala,ycho/daala