dnsmasq: avoid forwarding queries without a domain

dnsmasq: avoid forwarding queries without a domain

dnsmasq is forwarding a number of queries upstream that should not
be done.  There still remains an MX query for a plain name with no
domain specified that will be forwarded is dnsmasq has --domain=xxx
--local=/xxx/ specified. This does not happen with no domain name
and --local=// ... not a libvirt problem.

BTW, thanks again to Claudio Bley!