In previous ADSTs, DST-7 and DST-4 are used for length 4 and length
8/16/32, respectively. In this LGT experiment we explore transforms
between DST-4 and DST-7. When CONFIG_LGT flag is on, adst4 and adst8
are replaced by lgt4 and lgt8, the intermediate transforms with
pre-chosen parameters.

The LGTs applied here are lgt4_160 and lgt8_170, where the numbers
mean the self-loop weights times 100. The associated values for DST-7
and DST-4 are 100 and 200.

ovr_psnr:
lowres: -0.140
midres: -0.131
hdres: -0.078

These changes are not applied to the highbd scenario in the
current version.

Change-Id: I20600456da8766528b2b6b11aa28801e70af498e