Unfork ANS decode_coefs
Unfork ANS decode_coefs

This is less code and more like what we have in aom/master.

Change-Id: I3ca2b674e4ad9e2e211d08bb51d78549e8b63a54

GrokImageCompression/aom,GrokImageCompression/aom,mbebenita/aom,GrokImageCompression/aom,GrokImageCompression/aom,mbebenita/aom,smarter/aom,luctrudeau/aom,mbebenita/aom,mbebenita/aom,luctrudeau/aom,smarter/aom,luctrudeau/aom,GrokImageCompression/aom,smarter/aom,smarter/aom,luctrudeau/aom,mbebenita/aom,GrokImageCompression/aom,mbebenita/aom,smarter/aom,mbebenita/aom,luctrudeau/aom,mbebenita/aom,smarter/aom,mbebenita/aom,luctrudeau/aom