net: Add compat support for getsockopt (MCAST_MSFILTER)

This patch adds support for getsockopt for MCAST_MSFILTER for
both IPv4 and IPv6. It depends on the previous setsockopt patch,
and uses the same method.

Signed-off-by: David L Stevens <dlstevens@us.ibm.com>
Signed-off-by: YOSHIFUJI Hideaki <yoshfuji@linux-ipv6.org>
Signed-off-by: David S. Miller <davem@davemloft.net>
diff --git a/include/net/compat.h b/include/net/compat.h
index 05fa5d0..164cb68 100644
--- a/include/net/compat.h
+++ b/include/net/compat.h
@@ -42,5 +42,8 @@
 
 extern int compat_mc_setsockopt(struct sock *, int, int, char __user *, int,
 	int (*)(struct sock *, int, int, char __user *, int));
+extern int compat_mc_getsockopt(struct sock *, int, int, char __user *,
+	int __user *, int (*)(struct sock *, int, int, char __user *,
+				int __user *));
 
 #endif /* NET_COMPAT_H */