test: use port number from env in tls socket test

Tests normally use common.PORT to allow the user to select which port
number to listen on. Hardcoding the port number will cause parallel
instances of the test to fail.

PR-URL: https://github.com/nodejs/node/pull/3557
Reviewed-By: Ben Noordhuis <info@bnoordhuis.nl>
Reviewed-By: Fedor Indutny <fedor@indutny.com>
Reviewed-By: Johan Bergström <bugs@bergstroem.nu>

test/parallel/test-tls-async-cb-after-socket-end.js

@@ -36,9 +36,9 @@ server.on('resumeSession', function(id, cb) {
   next();
 });
 
-server.listen(1443, function() {
+server.listen(common.PORT, function() {
   var clientOpts = {
-    port: 1443,
+    port: common.PORT,
     rejectUnauthorized: false,
     session: false
   };