resolver: Return error looking up invalid hostnames
resolver: Return error looking up invalid hostnames

Make g_resolver_lookup_by_name() and g_resolver_lookup_by_name_async()
error out when invalid hostnames are passed.

https://bugzilla.gnome.org/show_bug.cgi?id=772989

johne53/MB3Glib,johne53/MB3Glib,johne53/MB3Glib,endlessm/glib,johne53/MB3Glib,endlessm/glib,endlessm/glib,endlessm/glib,johne53/MB3Glib,johne53/MB3Glib,endlessm/glib