This patch reverts ca4782bb: Disable daala_ec when ext_tile is enabled.
Certain tests in superframe_test.cc were disabled for only ans that
 should have been disabled for both ans and daala_ec.
This was corrected in d526d0a8 and now the unit tests pass with
 --enable-daala_ec and --enable-ext_tile.

Change-Id: I76244bb4d687040dbd504475c31361933830943d