The commits d57567940153147f4d43875fb92c3030b3178b03 and
080bf330e3749d94ebe094f8deca0e3e67d3f2fe made use directly of
macro defined in recent linux netlink version. Make those
part conditional on the definition
* daemon/libvirtd.c: do not use NETLINK_ROUTE and NETLINK_KOBJECT_UEVENT
without some check first