[IPV6]: Make the ipv6/sysctl_net_ipv6.c compilation cleaner

Since this file is entirely enclosed with the
#ifdef CONFIG_SYSCTL/#endif pair, it's OK to move this
CONFIG_ into a Makefile.

Signed-off-by: Pavel Emelyanov <xemul@openvz.org>
Signed-off-by: David S. Miller <davem@davemloft.net>
diff --git a/net/ipv6/Makefile b/net/ipv6/Makefile
index 5ffa980..24f3aa0 100644
--- a/net/ipv6/Makefile
+++ b/net/ipv6/Makefile
@@ -8,9 +8,9 @@
 		addrlabel.o \
 		route.o ip6_fib.o ipv6_sockglue.o ndisc.o udp.o udplite.o \
 		raw.o protocol.o icmp.o mcast.o reassembly.o tcp_ipv6.o \
-		exthdrs.o sysctl_net_ipv6.o datagram.o \
-		ip6_flowlabel.o inet6_connection_sock.o
+		exthdrs.o datagram.o ip6_flowlabel.o inet6_connection_sock.o
 
+ipv6-$(CONFIG_SYSCTL) = sysctl_net_ipv6.o
 ipv6-$(CONFIG_XFRM) += xfrm6_policy.o xfrm6_state.o xfrm6_input.o \
 	xfrm6_output.o
 ipv6-$(CONFIG_NETFILTER) += netfilter.o