fix build for windows (#366)

Summary:
Pull Request resolved: #366

windows has the call in a different header so need to handle that

Differential Revision: D47562408

fbshipit-source-id: 31c48f72c6b8984ba390edee281a72d75faa4a90

Author: xunnanxu

gloo/common/utils.cc

@@ -7,7 +7,12 @@
  */
 
 #include <system_error>
+
+#ifdef _WIN32
+#include <winsock2.h>
+#else
 #include <unistd.h>
+#endif
 
 #include "gloo/common/utils.h"
 

gloo/rendezvous/context.cc

@@ -13,13 +13,6 @@
 #include "gloo/common/logging.h"
 #include "gloo/transport/address.h"
 
-#ifdef _WIN32
-#include <winsock2.h>
-#include <gloo/common/win.h>
-#else
-#include <unistd.h>
-#endif
-
 namespace gloo {
 namespace rendezvous {