gcc3 compatibility: removed ARP_NET_PROTOCOL().

src/include/gpxe/arp.h

 			  const void *net_addr );
 };
 
-/**
- * Register an ARP protocol
- *
- * @v protocol		ARP protocol
- */
-#define ARP_NET_PROTOCOL( protocol ) \
-	struct arp_net_protocol protocol __table ( arp_net_protocols, 01 )
+/** Declare an ARP protocol */
+#define __arp_net_protocol __table ( arp_net_protocols, 01 )
 
 extern int arp_resolve ( struct net_device *netdev,
 			 struct net_protocol *net_protocol,

src/net/ipv4.c

 TCPIP_NET_PROTOCOL ( ipv4_tcpip_protocol );
 
 /** IPv4 ARP protocol */
-struct arp_net_protocol ipv4_arp_protocol = {
+struct arp_net_protocol ipv4_arp_protocol __arp_net_protocol = {
 	.net_protocol = &ipv4_protocol,
 	.check = ipv4_arp_check,
 };
-
-ARP_NET_PROTOCOL ( ipv4_arp_protocol );