test: kill children before cluster parent

Killing the cluster master first on Windows causes an ESRCH when killing
the children as the OS takes care of them itself.

PR-URL: node-forward/node#53
Reviewed-By: Ben Noordhuis <info@bnoordhuis.nl>

test/simple/test-debug-signal-cluster.js

@@ -73,7 +73,9 @@ setTimeout(function testTimedOut() {
 }, 6000);
 
 process.on('exit', function onExit() {
-  pids.forEach(function(pid) {
+  // Kill processes in reverse order to avoid timing problems on Windows where
+  // the parent process is killed before the children.
+  pids.reverse().forEach(function(pid) {
     process.kill(pid);
   });
 });