Add FEATURE() macro, plus code to display features at startup time,

and generate DHCP options to indicate features to DHCP server (and to
PXE NBPs).

src/net/aoe.c

@@ -31,6 +31,7 @@
 #include <gpxe/ata.h>
 #include <gpxe/netdevice.h>
 #include <gpxe/process.h>
+#include <gpxe/features.h>
 #include <gpxe/aoe.h>
 
 /** @file
@@ -39,6 +40,8 @@
  *
  */
 
+FEATURE ( "AoE", DHCP_EB_FEATURE_AOE );
+
 struct net_protocol aoe_protocol;
 
 /** List of all AoE sessions */