1) Turn off SIMD quantizer in adapt_scan experiment because the iscan is
not 16-byte aligned now.

2) Turn off eob-specific dqcoeff initialization in
inverse_transform_block_inter and inverse_transform_block_intra

3) Turn off transform optimization for special eob because it is not
compatible with adapt_scan experiment

Performance:
        PSNR    BDRate
lowres  1.2%    1.068%
midres  0.897%  0.769%
hdres   0.945%  0.724%

Change-Id: I197c19ba536761c334790a040ef44534c7cf21b5