doc/ffmpeg: document -override_ffserver

Signed-off-by: Michael Niedermayer <michaelni@gmx.at>
mjpeg_decode_scan: reset restart state

Fixes Ticket2082
Fixes progressive/refinement + restart jpegs

Signed-off-by: Michael Niedermayer <michaelni@gmx.at>
jpegdec: give handle_rstn() a return code that indicates if restart did happen

Signed-off-by: Michael Niedermayer <michaelni@gmx.at>
jpegdec: clear EOBRUN on restarts

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