avformat/network: check ff_socket_nonblock() return and print a debug message

Fixes CID1026744
Fixes CID1026743

Signed-off-by: Michael Niedermayer <michaelni@gmx.at>
avformat/ipmovie: Fix use of uninitialized memory in OPCODE_INIT_VIDEO_BUFFERS

Fixes: msan_uninit-mem_7ffe323a25f3_5929_ipmovie_interplayvideo_interplay_dpcm__bislogo.mve
Found-by: Mateusz "j00ru" Jurczyk and Gynvael Coldwind
Signed-off-by: Michael Niedermayer <michaelni@gmx.at>
avcodec/mjpegdec: use mallocz for progressive blocks

Fixes use of uninitialized memory
Fixes: msan_uninit-mem_7f849c599487_6828_mjpeg.avi
Found-by: Mateusz "j00ru" Jurczyk and Gynvael Coldwind
Signed-off-by: Michael Niedermayer <michaelni@gmx.at>