Fix uninitialized context use case in supertx and var-tx
Fix uninitialized context use case in supertx and var-tx

This commit fixes the use of uninitialized context values in the
combination of supertx and var-tx.

Change-Id: I2d36badf5c9806ea402ce3e19515cc299e6b79e8

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