Patch from Mato that fixes a subtle connect bug: EAGAIN was being used as a…

Patch from Mato that fixes a subtle connect bug: EAGAIN was being used as a translation value for EINPROGRESS, thus
shadowing a real EAGAIN return value from the OS.  This caused later
assertions of "Invalid argument" in stream_engine.cpp when it attempted to
use a socket which was not connected.

I also add EINTR to mean EINPROGRESS, as per the POSIX and FreeBSD
documentation which specifies that a connect() call interrupted due to a
signal will complete asynchronously.
Signed-off-by: Martin Lucina <martin@lucina.net>

src/ipc_connecter.cpp

@@ -187,6 +187,13 @@ int zmq::ipc_connecter_t::open ()
     if (rc == 0)
         return 0;
         
+    //  Translate other error codes indicating asynchronous connect has been
+    //  launched to a uniform EINPROGRESS.
+    if (rc == -1 && errno == EINTR) {
+        errno = EINPROGRESS;
+        return -1;
+    }
+
     //  Forward the error.
     return -1;
 }

src/tcp_connecter.cpp

@@ -140,7 +140,7 @@ void zmq::tcp_connecter_t::start_connecting ()
     }
 
     //  Connection establishment may be delayed. Poll for its completion.
-    else if (rc == -1 && errno == EAGAIN) {
+    else if (rc == -1 && errno == EINPROGRESS) {
         handle = add_fd (s);
         handle_valid = true;
         set_pollout (handle);
@@ -211,17 +211,18 @@ int zmq::tcp_connecter_t::open ()
     if (rc == 0)
         return 0;
 
-    //  Asynchronous connect was launched.
+    //  Translate other error codes indicating asynchronous connect has been
+    //  launched to a uniform EINPROGRESS.
 #ifdef ZMQ_HAVE_WINDOWS
     if (rc == SOCKET_ERROR && (WSAGetLastError () == WSAEINPROGRESS ||
           WSAGetLastError () == WSAEWOULDBLOCK)) {
-        errno = EAGAIN;
+        errno = EINPROGRESS;
         return -1;
     }    
     wsa_error_to_errno ();
 #else
-    if (rc == -1 && errno == EINPROGRESS) {
-        errno = EAGAIN;
+    if (rc == -1 && errno == EINTR) {
+        errno = EINPROGRESS;
         return -1;
     }
 #endif