Fix TestSuperframeIndexIsOptional to work with daala_ec.
Fix TestSuperframeIndexIsOptional to work with daala_ec.

The superframe index is also mandatory with daala_ec for the same
 reason it is mandatory with ans, e.g., with both entropy coder
 backends the buffer length is not known when calling aom_reader_init(),
 see commit 15c1aa60f33e569305e5ce1f551c7bbebb272459.
This patch disables the same tests for CONFIG_DAALA_EC that are disabled
 when CONFIG_ANS is enabled with CONFIG_EXT_TILE.

BUG=aomedia:116

Change-Id: Icc89a01492296d56abfb966093a3c06f2f228650

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