Add NSLOOKUP and NTP commands to netboot.xyz

ipxe/local/general.h

@@ -5,3 +5,5 @@
 #define NET_PROTO_IPV6        /* IPv6 protocol */
 #define REBOOT_CMD            /* Reboot command */
 #define VLAN_CMD              /* VLAN commands */
+#define NSLOOKUP_CMD	      /* DNS resolving command */
+#define NTP_CMD               /* NTP commands */