NFS: Update MNT and MNT3 reply decoding functions

Solder xdr_stream-based XDR decoding functions into the in-kernel mountd
client that are more careful about checking data types and watching for
buffer overflows.  The new MNT3 decoder includes support for auth-flavor
list decoding.

The "_sz" macro for MNT3 replies was missing the size of the file handle.
I've added this back, and included the size of the auth flavor array.

Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
Signed-off-by: Trond Myklebust <Trond.Myklebust@netapp.com>
diff --git a/fs/nfs/internal.h b/fs/nfs/internal.h
index 0207758..10cf111 100644
--- a/fs/nfs/internal.h
+++ b/fs/nfs/internal.h
@@ -83,6 +83,8 @@
 	unsigned short		protocol;
 	struct nfs_fh		*fh;
 	int			noresvport;
+	unsigned int		*auth_flav_len;
+	rpc_authflavor_t	*auth_flavs;
 };
 
 extern int nfs_mount(struct nfs_mount_request *info);