Revert "Removed unreachable code paths"

This reverts commit 4f77cfa3.

src/signaler.cpp

@@ -184,10 +184,15 @@ void zmq::signaler_t::send ()
     errno_assert (sz == sizeof (inc));
 #elif defined ZMQ_HAVE_WINDOWS
     unsigned char dummy = 0;
-    const int nbytes =
-      ::send (_w, reinterpret_cast<char *> (&dummy), sizeof (dummy), 0);
-    wsa_assert (nbytes != SOCKET_ERROR);
-    zmq_assert (nbytes == sizeof (dummy));
+    while (true) {
+        int nbytes =
+          ::send (_w, reinterpret_cast<char *> (&dummy), sizeof (dummy), 0);
+        wsa_assert (nbytes != SOCKET_ERROR);
+        if (unlikely (nbytes == SOCKET_ERROR))
+            continue;
+        zmq_assert (nbytes == sizeof (dummy));
+        break;
+    }
 #elif defined ZMQ_HAVE_VXWORKS
     unsigned char dummy = 0;
     while (true) {