test: fix missing unistd.h on windows

PR-URL: https://github.com/nodejs/node/pull/3532
Reviewed-By: Ben Noordhuis <info@bnoordhuis.nl>

test/addons/async-hello-world/binding.cc

@@ -1,8 +1,14 @@
-#include <unistd.h>
 #include <node.h>
 #include <v8.h>
 #include <uv.h>
 
+#if defined _WIN32
+#include <windows.h>
+#else
+#include <unistd.h>
+#endif
+
+
 struct async_req {
   uv_work_t req;
   int input;
@@ -13,7 +19,12 @@ struct async_req {
 
 void DoAsync(uv_work_t* r) {
   async_req* req = reinterpret_cast<async_req*>(r->data);
-  sleep(1);  // Simulate CPU intensive process...
+  // Simulate CPU intensive process...
+#if defined _WIN32
+  Sleep(1000);
+#else
+  sleep(1);
+#endif
   req->output = req->input * 2;
 }