avformat: Read errno before av_log() as the callback from av_log() might affect errno

Signed-off-by: Michael Niedermayer <michaelni@gmx.at>
tools/ffhash: read errno before calling functions which might change it

Signed-off-by: Michael Niedermayer <michaelni@gmx.at>
avformat/rtpdec_asf: Use av_find_input_format() instead of directly linking to the demuxer

Signed-off-by: Michael Niedermayer <michaelni@gmx.at>
avformat/mpeg: Use av_find_input_format() instead of directly linking to the demuxer

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