support '-' salt in rndc signing -nsec3param

3361.	[bug]		"rndc signing -nsec3param" didn't work correctly
			when salt was set to '-' (no salt). [RT #30099]

bin/tests/system/dnssec/ns3/inline.example.db

@@ -0,0 +1,32 @@
+; Copyright (C) 2004, 2007  Internet Systems Consortium, Inc. ("ISC")
+; Copyright (C) 2000, 2001  Internet Software Consortium.
+;
+; Permission to use, copy, modify, and/or distribute this software for any
+; purpose with or without fee is hereby granted, provided that the above
+; copyright notice and this permission notice appear in all copies.
+;
+; THE SOFTWARE IS PROVIDED "AS IS" AND ISC DISCLAIMS ALL WARRANTIES WITH
+; REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF MERCHANTABILITY
+; AND FITNESS.  IN NO EVENT SHALL ISC BE LIABLE FOR ANY SPECIAL, DIRECT,
+; INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING FROM
+; LOSS OF USE, DATA OR PROFITS, WHETHER IN AN ACTION OF CONTRACT, NEGLIGENCE
+; OR OTHER TORTIOUS ACTION, ARISING OUT OF OR IN CONNECTION WITH THE USE OR
+; PERFORMANCE OF THIS SOFTWARE.
+
+; $Id: insecure.example.db,v 1.9 2007/06/19 23:47:02 tbox Exp $
+
+$TTL 300	; 5 minutes
+@			IN SOA	mname1. . (
+				2000042407 ; serial
+				20         ; refresh (20 seconds)
+				20         ; retry (20 seconds)
+				1814400    ; expire (3 weeks)
+				3600       ; minimum (1 hour)
+				)
+			NS	ns
+ns			A	10.53.0.3
+
+a			A	10.0.0.1
+b			A	10.0.0.2
+d			A	10.0.0.4
+z			A	10.0.0.26

bin/tests/system/dnssec/ns3/named.conf

@@ -255,4 +255,11 @@ zone "LOWER.EXAMPLE" {
 	file "lower.example.db.signed";
 };
 
+zone "inline.example" {
+        type master;
+        file "inline.example.db";
+        inline-signing yes;
+        auto-dnssec maintain;
+};
+
 include "trusted.conf";

bin/tests/system/dnssec/ns3/sign.sh

@@ -429,3 +429,9 @@ $CHECKZONE -D nosign.example nosign.example.db.signed 2>&- | \
         awk '$4 == "RRSIG" && $5 == "NS" {$2 = ""; print}' | \
         sed 's/[ 	][ 	]*/ /g'> ../nosign.before
 
+#
+# An inline signing zone
+#
+zone=inline.example.
+kskname=`$KEYGEN -q -3 -r $RANDFILE -fk $zone`
+zskname=`$KEYGEN -q -3 -r $RANDFILE $zone`