avcodec/atrac3plus: Run-length encode length tables to make them smaller

avcodec/atrac3plus: Run-length encode length tables to make them smaller

This is very beneficial for the scale factor tables where 4*64+4*15
bytes of length information can be replaced by eight codebooks of 12
bytes each; furthermore the number of codes as well as the maximum
length of a code can be easily derived from said codebooks, making
tables containing said information superfluous. This and combining the
symbols into one big array also made an array of pointers to the tables
redundant.

For the wordlen and code table tables the benefits are not that big
(given these tables don't contain that many elements), but all in all
using codebooks is also advantageouos for them. Therefore it has been
done.

Signed-off-by: Andreas Rheinhardt <andreas.rheinhardt@gmail.com>