Switching from ff_init_vlc_sparse() to ff_init_vlc_from_lengths()
allows to replace codes which are so long that they need to be stored
in an uint16_t by symbols which fit into an uint8_t; furthermore, it is
also easily possible to already incorporate the offset (the real range
of Indeo 2 symbols starts at one, not zero) into the symbols.
Signed-off-by: Andreas Rheinhardt <andreas.rheinhardt@gmail.com>