[libvirt] Proposed: replace radvd with dnsmasq for Router Advertizing

I have been doing some testing and dnsmasq is capable of handling the service currently provided by radvd. To implement this in dnsmasq requires the following: if an IPv6 dhcp-range is specified, then add: enable-ra if no IPv6 dhcp-range is specified, then add: dhsp-range=<IPv6-subnet>,ra-only Tested. The second one will work with basic dnsmasq-2.6.3. The first one and dhcp-range itself only works with dnsmasq-2.64 (when released) or dnsmasq-2.63+patches. Since dnsmasq-2.48 does not support IPv6 dhcp but does handle IPv6 for dns and CentOS 6 does include radvd, I also propose that a libvirtd.conf option be added. If the option is not present or set off, then radvd is used. If the option is set on, then dnsmasq is used. At some point in the future, it can be decided whether to keep using radvd or not. Comments? Suggestions? Gene