ans: Refill state at the end of the decoding process.
This should have no effect on the bitstream format (see also no related encoder change). This is like moving code from the top of the loop to the bottom of the loop. This change allows us to: * Make sure we consume the final renormalization byte after the last symbol in an ANS partition. * Move back toward a single renormalization operation for some ANS modes since we know the bounds of the state mutation algorithm that got us out of the valid state range. Change-Id: Ia80246fd0ed805aa61b913a362546b3f08e4d79c