Fix forcing multicast msgs to loopback on OpenBSD.

Fix forcing multicast msgs to loopback on OpenBSD.
e.g.
$ sudo qemu -m 128 -no-fd-bootchk \
        -hda virtual.img -boot n -nographic \
        -net nic,vlan=0,model=rtl8139,macaddr=52:54:00:12:34:03 \
        -net user -tftp /usr/src/sys/arch/i386/compile/TEST -bootp pxeboot \
        -net nic,vlan=1,model=rtl8139,macaddr=52:54:00:23:03:01 \
        -net tap,vlan=1,script=no \
        -net nic,vlan=3,model=rtl8139,macaddr=52:54:00:23:03:03 \
        -net socket,vlan=3,mcast=230.0.0.1:10003
setsockopt(SOL_IP, IP_MULTICAST_LOOP): Invalid argument
qemu: -net socket,vlan=3,mcast=230.0.0.1:10003: Device 'socket' could not be initialized
Signed-off-by: NBrad Smith <brad@comstyle.com>
Signed-off-by: NBlue Swirl <blauwirbel@gmail.com>

net/socket.c

@@ -154,6 +154,12 @@ static int net_socket_mcast_create(struct sockaddr_in *mcastaddr, struct in_addr
     struct ip_mreq imr;
     int fd;
     int val, ret;
+#ifdef __OpenBSD__
+    unsigned char loop;
+#else
+    int loop;
+#endif
+
     if (!IN_MULTICAST(ntohl(mcastaddr->sin_addr.s_addr))) {
 	fprintf(stderr, "qemu: error: specified mcastaddr \"%s\" (0x%08x) does not contain a multicast address\n",
 		inet_ntoa(mcastaddr->sin_addr),
@@ -197,9 +203,9 @@ static int net_socket_mcast_create(struct sockaddr_in *mcastaddr, struct in_addr
     }
 
     /* Force mcast msgs to loopback (eg. several QEMUs in same host */
-    val = 1;
+    loop = 1;
     ret=setsockopt(fd, IPPROTO_IP, IP_MULTICAST_LOOP,
-                   (const char *)&val, sizeof(val));
+                   (const char *)&loop, sizeof(loop));
     if (ret < 0) {
 	perror("setsockopt(SOL_IP, IP_MULTICAST_LOOP)");
 	goto fail;