Fix the superframe unit test for ext-refs
Fix the superframe unit test for ext-refs

Change-Id: I64b236d859a50a265b9b9ee2315bf2549e63881d

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