Fix problem with domains associated with DHCP hosts at startup.

At startup, the leases file is read by lease_init(), and
in lease_init() undecorated hostnames are expanded into
FQDNs by adding the domain associated with the address
of the lease.

lease_init() happens relavtively early in the startup, party because
if it calls  the dhcp-lease helper script, we don't want that to inherit
a load of sensitive file descriptors. This has implications if domains
are defined using the --domain=example.com,eth0 format since it's long
before we call enumerate_interfaces(), so get_domain fails for such domains.

The patch just moves the hostname expansion function to a seperate
subroutine that gets called later, after enumerate_interfaces().

src/dnsmasq.c

@@ -374,6 +374,13 @@ int main (int argc, char **argv)
   
   if (!enumerate_interfaces(1) || !enumerate_interfaces(0))
     die(_("failed to find list of interfaces: %s"), NULL, EC_MISC);
+
+#ifdef HAVE_DHCP
+  /* Determine lease FQDNs after enumerate_interfaces() call, since it needs
+     to call get_domain and that's only valid for some domain configs once we
+     have interface addresses. */
+  lease_calc_fqdns();
+#endif
   
   if (option_bool(OPT_NOWILD) || option_bool(OPT_CLEVERBIND)) 
     {