Fix some avi rawvideo formats on big endian.

Fixes ticket #2196.
Write forced track flag to matroska files.

Based on a patch by Daniel Pielmeier, daniel pielmeier gmail
Fixes a part of ticket #1815.
mjpegdec: fix memcmp size for *_count

Fixes assertion failure

Found-by: Mateusz "j00ru" Jurczyk and Gynvael Coldwind
Signed-off-by: Michael Niedermayer <michaelni@gmx.at>
aacdec: check init_get_bits return

Also fixes an integer overflow

Signed-off-by: Michael Niedermayer <michaelni@gmx.at>
mjpegdec: rgb mode is specific for ljpeg, disable it for others.

Fixes null pointer dereference

Found-by: Mateusz "j00ru" Jurczyk and Gynvael Coldwind
Signed-off-by: Michael Niedermayer <michaelni@gmx.at>
lavd/v4l2: use avcodec_find_decoder in list_formats

Because libavdevice/v4l2 is a demuxer, it makes sense to look for
decoders instead of encoders when listing the formats supported by the
device.

Signed-off-by: Stefano Sabatini <stefasab@gmail.com>
aasc: fix 16bpp on big-endian