udhcp: optional support for non-standard DHCP ports (+300 bytes when selected)

diff --git a/networking/udhcp/dhcprelay.c b/networking/udhcp/dhcprelay.c
index c243cc1..def1bc2 100644
--- a/networking/udhcp/dhcprelay.c
+++ b/networking/udhcp/dhcprelay.c
@@ -14,6 +14,7 @@
 #include "options.h"
 
 /* constants */
+#define SERVER_PORT      67
 #define SELECT_TIMEOUT    5 /* select timeout in sec. */
 #define MAX_LIFETIME   2*60 /* lifetime of an xid entry in sec. */