NFSD: Pack struct nfsd4_compoundres

Remove a couple of 4-byte holes on platforms with 64-bit pointers.
Signed-off-by: Chuck Lever <chuck.lever@oracle.com>

fs/nfsd/xdr4.h

@@ -732,8 +732,8 @@ struct nfsd4_compoundres {
 	struct svc_rqst *		rqstp;
 
 	__be32				*statusp;
-	u32				taglen;
 	char *				tag;
+	u32				taglen;
 	u32				opcnt;
 
 	struct nfsd4_compound_state	cstate;