test: fix tests when npn feature is disabled.

ALPN test needs NPN feature to run. It also change the messages when
ALPN and NPN tests are skipped.

Fixes: https://github.com/nodejs/node/issues/11650
PR-URL: https://github.com/nodejs/node/pull/11655
Reviewed-By: James M Snell <jasnell@gmail.com>
Reviewed-By: Michael Dawson <michael_dawson@ca.ibm.com>
Reviewed-By: Ben Noordhuis <info@bnoordhuis.nl>
Reviewed-By: Fedor Indutny <fedor@indutny.com>

test/parallel/test-tls-alpn-server-client.js

@@ -6,10 +6,10 @@ if (!common.hasCrypto) {
   return;
 }
 
-if (!process.features.tls_alpn) {
+if (!process.features.tls_alpn || !process.features.tls_npn) {
-  console.error('Skipping because node compiled without OpenSSL or ' +
+  common.skip('Skipping because node compiled without NPN or ALPN' +
-                'with old OpenSSL version.');
+              ' feature of OpenSSL.');
-  process.exit(0);
+  return;
 }
 
 const assert = require('assert');

test/parallel/test-tls-npn-server-client.js

@@ -1,8 +1,8 @@
 'use strict';
 const common = require('../common');
 if (!process.features.tls_npn) {
-  common.skip('node compiled without OpenSSL or ' +
+  common.skip('Skipping because node compiled without NPN feature of' +
-              'with old OpenSSL version.');
+              ' OpenSSL.');
   return;
 }