Use prereq.sh for serve-stale system test

bin/tests/system/Makefile.am

@@ -72,10 +72,6 @@ rpz_dnsrps_LDADD =		\
 
 TESTS =
 
-if HAVE_PERLMOD_TIME_HIRES
-TESTS += serve-stale
-endif HAVE_PERLMOD_TIME_HIRES
-
 if HAVE_PERLMOD_NET_DNS
 TESTS +=		\
 	rpzrecurse
@@ -163,6 +159,7 @@ TESTS +=			\
 	rrsetorder		\
 	rsabigexponent		\
 	runtime			\
+	serve-stale		\
 	sfcache			\
 	shutdown		\
 	smartsign		\

bin/tests/system/serve-stale/prereq.sh

@@ -0,0 +1,22 @@
+#!/bin/sh
+
+# Copyright (C) Internet Systems Consortium, Inc. ("ISC")
+#
+# SPDX-License-Identifier: MPL-2.0
+#
+# This Source Code Form is subject to the terms of the Mozilla Public
+# License, v. 2.0.  If a copy of the MPL was not distributed with this
+# file, you can obtain one at https://mozilla.org/MPL/2.0/.
+#
+# See the COPYRIGHT file distributed with this work for additional
+# information regarding copyright ownership.
+
+. ../conf.sh
+
+if ! ${PERL} -MTime::HiRes -e ''
+then
+	echo_i "perl Time::HiRes module is required"
+	exit 1
+fi
+
+exit 0

configure.ac

@@ -315,10 +315,6 @@ AX_PERL_MODULE([Net::DNS])
 AM_CONDITIONAL([HAVE_PERLMOD_NET_DNS],
 	       [test "$HAVE_PERLMOD_NET__DNS" = "yes"])
 
-AX_PERL_MODULE([Time::HiRes])
-AM_CONDITIONAL([HAVE_PERLMOD_TIME_HIRES],
-	       [test "$HAVE_PERLMOD_TIME__HIRES" = "yes"])
-
 #
 # Python is optional, it is used only by some of the system test scripts.
 #