[DCCP]: fix link error with !CONFIG_SYSCTL

Do not define the sysctl_dccp_sync_ratelimit sysctl variable in the
CONFIG_SYSCTL dependent sysctl.c module - move it to input.c instead.

This fixes the following build bug:

 net/built-in.o: In function `dccp_check_seqno':
 input.c:(.text+0xbd859): undefined reference to `sysctl_dccp_sync_ratelimit'
 distcc[29953] ERROR: compile (null) on localhost failed
 make: *** [vmlinux] Error 1

Found via 'make randconfig' build testing.
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Acked-by: Ian McDonald <ian.mcdonald@jandi.co.nz>
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: David S. Miller <davem@davemloft.net>

net/dccp/input.c

@@ -19,6 +19,9 @@
 #include "ccid.h"
 #include "dccp.h"
 
+/* rate-limit for syncs in reply to sequence-invalid packets; RFC 4340, 7.5.4 */
+int sysctl_dccp_sync_ratelimit	__read_mostly = HZ / 8;
+
 static void dccp_fin(struct sock *sk, struct sk_buff *skb)
 {
 	sk->sk_shutdown |= RCV_SHUTDOWN;

net/dccp/sysctl.c

@@ -18,9 +18,6 @@
 #error This file should not be compiled without CONFIG_SYSCTL defined
 #endif
 
-/* rate-limit for syncs in reply to sequence-invalid packets; RFC 4340, 7.5.4 */
-int sysctl_dccp_sync_ratelimit	__read_mostly = HZ / 8;
-
 static struct ctl_table dccp_default_table[] = {
 	{
 		.procname	= "seq_window",