Fixes out of array access
Fixes: ffmpeg_opus_crash1.ogg

This solution is likely not optimal in terms of error concealment but
its simple and fixes the out of array access.
Found-by: Thomas Lindroth <thomas.lindroth@gmail.com>
Tested-by: Thomas Lindroth <thomas.lindroth@gmail.com>
Signed-off-by: Michael Niedermayer <michaelni@gmx.at>

This is safer than to assume that all error pathes cleared them and
nothing will use uncleared pointers.
Signed-off-by: Michael Niedermayer <michaelni@gmx.at>

Signed-off-by: Paul B Mahol <onemda@gmail.com>

Signed-off-by: Paul B Mahol <onemda@gmail.com>

Signed-off-by: Michael Niedermayer <michaelni@gmx.at>

Fixes invalid writes with invalid multichannel streams.

CC:libav-stable@libav.org

Signed-off-by: Michael Niedermayer <michaelni@gmx.at>

also make a const array static
Fixes 2 warnings
Signed-off-by: Michael Niedermayer <michaelni@gmx.at>

This also fixes linking failures in doc/examples which where apparently
caused by the linking order between avcodec and avresample
Signed-off-by: Michael Niedermayer <michaelni@gmx.at>

Initial implementation by Andrew D'Addesio <modchipv12@gmail.com> during
GSoC 2012.

Completion by Anton Khirnov <anton@khirnov.net>, sponsored by the
Mozilla Corporation.

Further contributions by:
Christophe Gisquet <christophe.gisquet@gmail.com>
Janne Grunau <janne-libav@jannau.net>
Luca Barbato <lu_zero@gentoo.org>