Keep track of zcoeff_blk in tx size/type search
Keep track of zcoeff_blk in tx size/type search

Prevent potential problems when per transform block
zero forcing is re-enabled (a To-Do).

Change-Id: I03b0ab2a86d88058441f2ca18994cfd2e6329898

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