The specification allows 2^32-1 to be encoded as any number of zeroes
greater than 31, followed by a one.  This previously failed because the
trace code would overflow the array containing the string representation
of the bits if there were more than 63 zeroes.  Fix that by splitting the
trace output into batches, and at the same time move it out of the default
path.

(While this seems likely to be a specification error, libaom does support
it so we probably should as well.)

From a test case by keval shah <skeval65@gmail.com>.
Reviewed-by: Michael Niedermayer <michael@niedermayer.cc>