fix of async connect on win32

src/tcp_connecter.cpp

@@ -180,8 +180,10 @@ int zmq::tcp_connecter_t::open ()
         return 0;
 
     //  Asynchronous connect was launched.
-    if (rc == -1 && errno == EINPROGRESS)
+    if (rc == -1 && errno == EINPROGRESS) {
+        errno = EAGAIN;
         return -1;
+    }
 
     //  Error occured.
     int err = errno;

src/zmq_connecter.cpp

@@ -100,7 +100,7 @@ void zmq::zmq_connecter_t::start_connecting ()
     }
 
     //  Connection establishment may be dealyed. Poll for its completion.
-    else if (rc == -1 && errno == EINPROGRESS) {
+    else if (rc == -1 && errno == EAGAIN) {
         handle = add_fd (tcp_connecter.get_fd ());
         handle_valid = true;
         set_pollout (handle);