ipv4,ipv6 mroute: Add some helper inline functions to remove ugly ifdefs.

ip{,v6}_mroute_{set,get}sockopt() should not matter by optimization but
it would be better not to depend on optimization semantically.

Signed-off-by: YOSHIFUJI Hideaki <yoshfuji@linux-ipv6.org>
diff --git a/include/linux/mroute.h b/include/linux/mroute.h
index df8efd4..07112ee 100644
--- a/include/linux/mroute.h
+++ b/include/linux/mroute.h
@@ -144,10 +144,37 @@
 }
 #endif
 
+#ifdef CONFIG_IP_MROUTE
 extern int ip_mroute_setsockopt(struct sock *, int, char __user *, int);
 extern int ip_mroute_getsockopt(struct sock *, int, char __user *, int __user *);
 extern int ipmr_ioctl(struct sock *sk, int cmd, void __user *arg);
 extern int ip_mr_init(void);
+#else
+static inline
+int ip_mroute_setsockopt(struct sock *sock,
+			 int optname, char __user *optval, int optlen)
+{
+	return -ENOPROTOOPT;
+}
+
+static inline
+int ip_mroute_getsockopt(struct sock *sock,
+			 int optname, char __user *optval, int __user *optlen)
+{
+	return -ENOPROTOOPT;
+}
+
+static inline
+int ipmr_ioctl(struct sock *sk, int cmd, void __user *arg)
+{
+	return -ENOIOCTLCMD;
+}
+
+static inline int ip_mr_init(void)
+{
+	return 0;
+}
+#endif
 
 struct vif_device
 {