Rename engine_pkcs11 system test

In order to have a common naming convention for system tests, rename the
only outlier "engine_pkcs11" to "enginepkcs11", which was the only
system test using an underscore in its name.

The only allowed word separators for system test names are either dash
or no separator.

bin/tests/system/enginepkcs11/prereq.sh

@@ -0,0 +1,21 @@
+#!/bin/sh -e
+#
+# 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 [ -n "${SOFTHSM2_MODULE}" ] && command -v softhsm2-util >/dev/null; then
+	exit 0
+fi
+
+echo_i "skip: softhsm2-util not available"
+exit 255