update_state: quiet const warning w/global-motion
update_state: quiet const warning w/global-motion

+ add a TODO as this is incompatible with tile-based threading

Change-Id: I057c551a5f19020366c6b85c2e67e8394bb3306f

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