test: check and fail inspector-cluster-port-clash

Currently this test fail when configured --without-inspector or
--without-ssl as it is expected to fail but the skipIfInspectorDisabled
check will exit as if the test was sucessful.

This commit checks if inspector support is available and fails the test
allowing the test to be skipped.

test/known_issues/test-inspector-cluster-port-clash.js

@@ -1,6 +1,7 @@
 // Flags: --inspect=0
 'use strict';
 const common = require('../common');
+const assert = require('assert');
 
 // With the current behavior of Node.js (at least as late as 8.1.0), this
 // test fails with the following error:
@@ -10,9 +11,13 @@ const common = require('../common');
 //
 // Refs: https://github.com/nodejs/node/issues/13343
 
-common.skipIfInspectorDisabled();
+if (process.config.variables.v8_enable_inspector === 0) {
+  // When the V8 inspector is disabled, using either --without-inspector or
+  // --without-ssl, this test will not fail which it is expected to do.
+  // The following fail will allow this test to be skipped by failing it.
+  assert.fail('skipping as V8 inspector is disabled');
+}
 
-const assert = require('assert');
 const cluster = require('cluster');
 const net = require('net');