Problem: C4800 warning in socket_base.cpp

Solution: make proper boolean expression

src/socket_base.cpp

@@ -210,7 +210,7 @@ zmq::socket_base_t::socket_base_t (ctx_t *parent_,
     options.socket_id = sid_;
     options.ipv6 = (parent_->get (ZMQ_IPV6) != 0);
     options.linger.store (parent_->get (ZMQ_BLOCKY) ? -1 : 0);
-    options.zero_copy = parent_->get (ZMQ_ZERO_COPY_RECV);
+    options.zero_copy = parent_->get (ZMQ_ZERO_COPY_RECV) != 0;
 
     if (thread_safe) {
         mailbox = new (std::nothrow) mailbox_safe_t (&sync);