avformat/network: check for fcntl() failure in ff_socket()

Fixes: CID1087075
Signed-off-by: Michael Niedermayer <michaelni@gmx.at>
avformat/oggparsecelt/celt_header: fix memleak

Fixes: CID1108605
Signed-off-by: Michael Niedermayer <michaelni@gmx.at>