Use correct protocol level for IP_MULTICAST_foo flags

The SOL_SOCKET protocol level works only on Linux, not on FreeBSD. The
IPPROTO_IP protocol level is the canonical, which both support, and is
also documented in Linux ip(7).

Signed-off-by: Joachim Wiberg <troglobit@gmail.com>

Author: troglobit

src/socket.c

@@ -111,11 +111,11 @@ int socket_create(int domain, int type, int proto, void (*cb)(int, void *), void
 		} else
 #endif /* HAVE_IPV6_MULTICAST_HOST */
 		{
-			if (setsockopt(sd, SOL_SOCKET, IP_MULTICAST_LOOP, &val, sizeof(val)))
+			if (setsockopt(sd, IPPROTO_IP, IP_MULTICAST_LOOP, &val, sizeof(val)))
 				smclog(LOG_WARNING, "failed disabling IP_MULTICAST_LOOP: %s",
 				       strerror(errno));
 #ifdef IP_MULTICAST_ALL
-			if (setsockopt(sd, SOL_SOCKET, IP_MULTICAST_ALL, &val, sizeof(val)))
+			if (setsockopt(sd, IPPROTO_IP, IP_MULTICAST_ALL, &val, sizeof(val)))
 				smclog(LOG_WARNING, "failed disabling IP_MULTICAST_ALL: %s",
 				       strerror(errno));
 #endif