[PATCH 2.4] fix THIS_MODULE error in arp.c

[Michael Buesch]

Hi Marcelo,

This fixes an "undeclared THIS_MODULE" compiletime error.

Sorry for the attachment. My mailer is currently broken and
corrupts diffs.
--- linux-2.4.28-rc1-bk4/net/ipv4/arp.c.orig	Sun Nov  7 15:27:45 2004
+++ linux-2.4.28-rc1-bk4/net/ipv4/arp.c	Sun Nov  7 15:28:42 2004
@@ -94,6 +94,7 @@
 #include <linux/stat.h>
 #include <linux/init.h>
 #include <linux/jhash.h>
+#include <linux/module.h>
 #ifdef CONFIG_SYSCTL
 #include <linux/sysctl.h>
 #endif