atrac3: fix error handling

decode_tonal_components returns a proper AVERROR.

Reported-by: Mateusz "j00ru" Jurczyk and Gynvael Coldwind
CC: libav-stable@libav.org
atrac3: set the getbits context the right buffer_end

Reported-by: Mateusz "j00ru" Jurczyk and Gynvael Coldwind
CC: libav-stable@libav.org
atrac3: Error on impossible encoding/channel combinations

Joint stereo encoded mono is impossible.

Reported-by: Mateusz "j00ru" Jurczyk and Gynvael Coldwind
CC: libav-stable@libav.org
imc: Catch a division by zero

Reported-by: Mateusz "j00ru" Jurczyk and Gynvael Coldwind
CC: libav-stable@libav.org
adpcm: Write the correct number of samples for ima-dk4

Reported-by: Mateusz "j00ru" Jurczyk and Gynvael Coldwind
CC: libav-stable@libav.org
qdm2: refactor joined stereo support

qdm2 does support only two channels. Loop over the run once.

Reported-by: Mateusz "j00ru" Jurczyk and Gynvael Coldwind
CC: libav-stable@libav.org
qdm2: Conceal broken samples

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