sock_diag: Arrange sock_diag.h such that it is exportable to userspace

Properly toss existing components around the ifdef __KERNEL__
and include the header into the header-y target.
Signed-off-by: Pavel Emelyanov <xemul@parallels.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

include/linux/Kbuild

@@ -195,6 +195,7 @@ header-y += igmp.h
 header-y += in.h
 header-y += in6.h
 header-y += in_route.h
+header-y += sock_diag.h
 header-y += inet_diag.h
 header-y += inotify.h
 header-y += input.h

include/linux/sock_diag.h

 #ifndef __SOCK_DIAG_H__
 #define __SOCK_DIAG_H__
 
-#define SOCK_DIAG_BY_FAMILY 20
+#include <linux/types.h>
 
-struct sk_buff;
-struct nlmsghdr;
+#define SOCK_DIAG_BY_FAMILY 20
 
 struct sock_diag_req {
 	__u8	sdiag_family;
 	__u8	sdiag_protocol;
 };
 
+#ifdef __KERNEL__
+struct sk_buff;
+struct nlmsghdr;
+
 struct sock_diag_handler {
 	__u8 family;
 	int (*dump)(struct sk_buff *skb, struct nlmsghdr *nlh);
@@ -26,4 +29,5 @@ int sock_diag_check_cookie(void *sk, __u32 *cookie);
 void sock_diag_save_cookie(void *sk, __u32 *cookie);
 
 extern struct sock *sock_diag_nlsk;
+#endif /* KERNEL */
 #endif