idcin: fix return check

CC: libav-stable@libav.org
Bug-Id: CID 732198
avio: fix sizeof argument

CC: libav-stable@libav.org
Bug-Id: CID 732284
aviobuf: check context before using it

Avoid a possible null pointer dereference.

CC: libav-stable@libav.org
Bug-Id: CID 1135769
wtv: check seek_by_sector return value

CC: libav-stable@libav.org
Bug-Id: CID 1198258
wtv: clean memory on error

CC: libav-stable@libav.org
Bug-Id: CID 718002
vf_format: check input validity

CC: libav-stable@libav.org
rtmpproto: remove dead code

Expression already evaluated before, redundant since
053386864219eccbcca1886c55f902f9555428a5.

Bug-Id: CID 732199
rtpdec_hevc: drop unnecessary check

len is always >=1 in that case.

Bug-Id: CID 1238784
nutdec: Prevent a memory corruption

Chapters do not have an event_flags field.

Bug-Id: CID 1231990
rtpproto: Free the addrinfo pointer on failure

CC: libav-stable@libav.org
Bug-Id: CID 1238797