test: prevent flakey test on pi2

Looping rapidly and making new connections causes problems on pi2.
Instead create a new connection when an old connection has already been
made. Running a stress test of 600 times and they all passed.

Fixes: nodejs#5302
PR-URL: nodejs#5537
Reviewed-By: Colin Ihrig <cjihrig@gmail.com>
Reviewed-By: Rich Trott <rtrott@gmail.com>
Reviewed-By: Alexis Campailla <orangemocha@nodejs.org>

test/parallel/parallel.status

@@ -10,7 +10,6 @@ prefix parallel
 test-tick-processor     : PASS,FLAKY
 
 [$system==linux]
-test-process-getactivehandles : PASS,FLAKY
 test-tick-processor           : PASS,FLAKY
 
 [$system==macos]

test/parallel/test-process-getactivehandles.js

@@ -10,13 +10,16 @@ var clients_counter = 0;
 
 const server = net.createServer(function listener(c) {
   connections.push(c);
-}).listen(common.PORT, function makeConnections() {
-  for (var i = 0; i < NUM; i++) {
-    net.connect(common.PORT, function connected() {
-      clientConnected(this);
-    });
-  }
-});
+}).listen(common.PORT, makeConnection);
+
+
+function makeConnection() {
+  if (clients_counter >= NUM) return;
+  net.connect(common.PORT, function connected() {
+    clientConnected(this);
+    makeConnection();
+  });
+}
 
 
 function clientConnected(client) {