[patch 09/12] avoid use of linux/if.h via linux/if_arp.h

Use <net/if_arp.h> rather than <linux/if_arp.h>,
otherwise you suck in <linux/if.h>, which conflicts with <net/if.h>
in glibc.

Signed-off-by: Erik van Konijnenburg <ekonijn@xs4all.nl>
diff --git a/ipconfig/main.c b/ipconfig/main.c
index fd038bc..84620d6 100644
--- a/ipconfig/main.c
+++ b/ipconfig/main.c
@@ -14,7 +14,7 @@
 #include <fcntl.h>
 #include <unistd.h>	/* for getopts */
 
-#include <linux/if_arp.h>
+#include <net/if_arp.h>
 
 #include "ipconfig.h"
 #include "netdev.h"