ans: Use a subnormal initial state

This saves the cost of encoding one symbol per partition. Currently in
practice this is usually the last DCT token sign so it saves one bit.
Most of the time these gains aren't realized but occasionally it makes
the final state one byte smaller or saves one renormalization.

Change-Id: Ibe5dc5d3471f51f932164b32e3bf28fb7b914805
2 files changed