SUNRPC: Change return value type of .pc_encode

Returning an undecorated integer is an age-old trope, but it's
not clear (even to previous experts in this code) that the only
valid return values are 1 and 0. These functions do not return
a negative errno, rpc_stat value, or a positive length.

Document there are only two valid return values by having
.pc_encode return only true or false.

Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
Signed-off-by: J. Bruce Fields <bfields@redhat.com>
diff --git a/fs/nfsd/nfsd.h b/fs/nfsd/nfsd.h
index 345f824..498e5a4 100644
--- a/fs/nfsd/nfsd.h
+++ b/fs/nfsd/nfsd.h
@@ -80,7 +80,7 @@ struct nfsd_voidargs { };
 struct nfsd_voidres { };
 bool		nfssvc_decode_voidarg(struct svc_rqst *rqstp,
 				      struct xdr_stream *xdr);
-int		nfssvc_encode_voidres(struct svc_rqst *rqstp,
+bool		nfssvc_encode_voidres(struct svc_rqst *rqstp,
 				      struct xdr_stream *xdr);
 
 /*