[NORMATIVE] mfmv adds candidate mv by comparison
[NORMATIVE] mfmv adds candidate mv by comparison

Sync with the design plan to use equality comparison to decide
if to add the mfmv into candidate list.

BUG=aomedia:1341

Change-Id: Ib01b32b9aeb48fb4b97b1ce008539184572a2655

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