test: require common module only once

Two tests were requiring the common module twice. This removes the
duplicate require statement in the tests.

PR-URL: #4611
Reviewed-By: Brian White <mscdex@mscdex.net>
Reviewed-By: Colin Ihrig <cjihrig@gmail.com>
Reviewed-By: Johan Bergström <bugs@bergstroem.nu>
Reviewed-By: James M Snell <jasnell@gmail.com>

Author: Trott

test/parallel/test-tls-0-dns-altname.js

@@ -10,8 +10,6 @@ var tls = require('tls');
 
 var fs = require('fs');
 
-var common = require('../common');
-
 var requests = 0;
 
 var server = tls.createServer({

test/parallel/test-tls-max-send-fragment.js

@@ -10,8 +10,6 @@ var tls = require('tls');
 
 var fs = require('fs');
 
-var common = require('../common');
-
 var buf = new Buffer(10000);
 var received = 0;
 var ended = 0;