finally fixing ipxe dns bug.

extra/pre-build.d/etc/resolvconf.conf

@@ -5,4 +5,4 @@ resolv_conf=/etc/resolv.conf
 # If you run a local name server, you should uncomment the below line and
 # configure your subscribers configuration files below.
 #name_servers=127.0.0.1
-name_servers='4.2.2.1 4.2.2.2 4.2.2.3'
+append_nameservers='4.2.2.1 4.2.2.2 4.2.2.3'