Re: [libvirt] [PATCH] network: always create dnsmasq hosts and addnhosts files, even if empty

This fixes the problem reported in: https://bugzilla.redhat.com/show_bug.cgi?id=868389 Previously, the dnsmasq hosts file (used for static dhcp entries, and addnhosts file (used for additional dns host entries) were only created/referenced on the dnsmasq commandline if there was something to put in them at the time the network was started. Once we can update a network definition while it's active (which is now possible with virNetworkUpdate), this is no longer a valid strategy - if there were 0 dhcp static hosts (resulting in no reference to the hosts file on the commandline), then one was later added, the commandline wouldn't have linked dnsmasq up to the file, so even though we create it, dnsmasq doesn't pay any attention. The solution is to just always create these files and reference them on the dnsmasq commandline (almost always, anyway). That way dnsmasq can notice when a new entry is added at runtime (a SIGHUP is sent to dnsmasq by virNetworkUdpate whenever a host entry is added or removed)