Avoid this warning like other uses of setsockopt:
/src/qemu/net/socket.c: In function 'net_socket_mcast_create':
/src/qemu/net/socket.c:210: warning: passing argument 4 of 'setsockopt' from incompatible pointer type
Signed-off-by: NBlue Swirl <blauwirbel@gmail.com>