avfilter/avfiltergraph: fix check using the wrong variables

Signed-off-by: Michael Niedermayer <michaelni@gmx.at>
avfilter/can_merge_formats: fix memleak

Signed-off-by: Michael Niedermayer <michaelni@gmx.at>
Allow native compilation on the iPhone.
Show max bitrate for mpeg2 video streams in avcodec_string().

See also 25b7aa9