Fix compilation on SSM-less operating systems

modules/misc/network/ipv6.c

@@ -242,6 +242,9 @@ static int OpenUDP( vlc_object_t * p_this )
         if ((*psz_server_addr)
          && ((U32_AT (&sock.sin6_addr) & 0xff30ffff) == 0xff300000))
         {
+#ifndef MCAST_JOIN_SOURCE_GROUP
+            errno = ENOSYS;
+#else
             struct group_source_req imr;
             struct sockaddr_in6 *p_sin6;
 
@@ -266,6 +269,7 @@ static int OpenUDP( vlc_object_t * p_this )
             msg_Dbg( p_this, "MCAST_JOIN_SOURCE_GROUP multicast request" );
             if( setsockopt( i_handle, IPPROTO_IPV6, MCAST_JOIN_SOURCE_GROUP,
                           (char *)&imr, sizeof(struct group_source_req) ) == -1 )
+#endif
             {
 
                 msg_Err( p_this, "Source specific multicast failed (%s) -"