Optimise od_dir_find8() for SSE4.1
Optimise od_dir_find8() for SSE4.1

Change-Id: I56a35b0d3d76294cc7b3d601770f7dcef12a8bc9

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