cabac: x86 version of get_cabac_bypass

Signed-off-by: Luca Barbato <lu_zero@gentoo.org>
indeo: use a typedef for the mc function pointer
indeo: Refactor ff_ivi_dec_huff_desc

Spare an indentation level.
indeo: Refactor ff_ivi_init_tiles and ivi_decode_blocks

Spin large and mostly self contained blocks into stand alone
functions.
indeo: Cosmetic formatting

Trim some overly long lines.
indeo: reject negative array indexes

Reported-by: Mateusz "j00ru" Jurczyk and Gynvael Coldwind
CC: libav-stable@libav.org