Add NCOBMC_ADAPT_WEIGHT experiment flag
Add NCOBMC_ADAPT_WEIGHT experiment flag

NCOBMC_ADAPT_WEIGHT allow using different interpolation kernels
to combine overlapped predictions generated using mvs in the
neighboring blocks.
This experiment will build on top of MOTION_VAR and it might conflict
with WARPED_MOTION in the developing stage, so will only be effective
when MOTION_VAR is on and WARPED_MOTION is off.

Change-Id: I4f1b6e55b6146ed443955751c09bfa22ef2f33e8

GrokImageCompression/aom,GrokImageCompression/aom,GrokImageCompression/aom,GrokImageCompression/aom,GrokImageCompression/aom,GrokImageCompression/aom