Use 4x4 granularity for nearest neighbor mv search
Use 4x4 granularity for nearest neighbor mv search

Search the immediate neighbor for reference motion vectors in the
unit of 4x4 block size. This improves the compression performance
by 0.05%.

Change-Id: Iaf04aa2c8986de6fbc22fd56e137c1f0bcb38185

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