ipv4: NET_IPV4_ROUTE_GC_INTERVAL removal

removing obsoleted sysctl,
ip_rt_gc_interval variable no longer used since 2.6.38

Signed-off-by: Vasily Averin <vvs@sw.ru>
Signed-off-by: David S. Miller <davem@davemloft.net>
diff --git a/include/linux/sysctl.h b/include/linux/sysctl.h
index 11684d9..9a1ec10 100644
--- a/include/linux/sysctl.h
+++ b/include/linux/sysctl.h
@@ -435,7 +435,7 @@
 	NET_IPV4_ROUTE_MAX_SIZE=5,
 	NET_IPV4_ROUTE_GC_MIN_INTERVAL=6,
 	NET_IPV4_ROUTE_GC_TIMEOUT=7,
-	NET_IPV4_ROUTE_GC_INTERVAL=8,
+	NET_IPV4_ROUTE_GC_INTERVAL=8, /* obsolete since 2.6.38 */
 	NET_IPV4_ROUTE_REDIRECT_LOAD=9,
 	NET_IPV4_ROUTE_REDIRECT_NUMBER=10,
 	NET_IPV4_ROUTE_REDIRECT_SILENCE=11,