[UDP]: Allow users to configure UDP-Lite.

Let's give users an option for disabling UDP-Lite (~4K).

old:
|    text	   data	    bss	    dec	    hex	filename
|  286498	  12432	   6072	 305002	  4a76a	net/ipv4/built-in.o
|  193830	   8192	   3204	 205226	  321aa	net/ipv6/ipv6.o

new (without UDP-Lite):
|    text	   data	    bss	    dec	    hex	filename
|  284086	  12136	   5432	 301654	  49a56	net/ipv4/built-in.o
|  191835	   7832	   3076	 202743	  317f7	net/ipv6/ipv6.o

Signed-off-by: YOSHIFUJI Hideaki <yoshfuji@linux-ipv6.org>
diff --git a/net/ipv4/af_inet.c b/net/ipv4/af_inet.c
index 4f539bd..67260c0 100644
--- a/net/ipv4/af_inet.c
+++ b/net/ipv4/af_inet.c
@@ -1317,15 +1317,18 @@
 	if (snmp_mib_init((void **)udp_statistics,
 			  sizeof(struct udp_mib)) < 0)
 		goto err_udp_mib;
+#ifdef CONFIG_IP_UDPLITE
 	if (snmp_mib_init((void **)udplite_statistics,
 			  sizeof(struct udp_mib)) < 0)
 		goto err_udplite_mib;
-
+#endif
 	tcp_mib_init();
 
 	return 0;
 
+#ifdef CONFIG_IP_UDPLITE
 err_udplite_mib:
+#endif
 	snmp_mib_free((void **)udp_statistics);
 err_udp_mib:
 	snmp_mib_free((void **)tcp_statistics);
@@ -1423,8 +1426,10 @@
 	/* Setup UDP memory threshold */
 	udp_init();
 
+#ifdef CONFIG_IP_UDPLITE
 	/* Add UDP-Lite (RFC 3828) */
 	udplite4_register();
+#endif
 
 	/*
 	 *	Set the ICMP layer up