IPv6: data structure changes for new socket options

Add underlying data structure changes and basic setsockopt()
and getsockopt() support for IPV6_RECVPATHMTU, IPV6_PATHMTU,
and IPV6_DONTFRAG.  IPV6_PATHMTU is actually fully functional
at this point.

Signed-off-by: Brian Haley <brian.haley@hp.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
diff --git a/include/linux/in6.h b/include/linux/in6.h
index 9b90cb2..c4bf46f 100644
--- a/include/linux/in6.h
+++ b/include/linux/in6.h
@@ -221,10 +221,10 @@
 #define IPV6_RTHDR		57
 #define IPV6_RECVDSTOPTS	58
 #define IPV6_DSTOPTS		59
-#if 0	/* not yet */
 #define IPV6_RECVPATHMTU	60
 #define IPV6_PATHMTU		61
 #define IPV6_DONTFRAG		62
+#if 0	/* not yet */
 #define IPV6_USE_MIN_MTU	63
 #endif