Problem: documented constants are not defined

Solution: add definition to zmq.h

include/zmq.h

@@ -723,6 +723,12 @@ ZMQ_EXPORT int zmq_socket_get_peer_state (void *socket,
                                           const void *routing_id,
                                           size_t routing_id_size);
 
+#define ZMQ_CURRENT_EVENT_VERSION 1
+#define ZMQ_CURRENT_EVENT_VERSION_DRAFT 2
+
+#define ZMQ_EVENT_ALL_V1 ZMQ_EVENT_ALL
+#define ZMQ_EVENT_ALL_V2 ZMQ_EVENT_ALL_V1
+
 ZMQ_EXPORT int zmq_socket_monitor_versioned (void *s_,
                                              const char *addr_,
                                              uint64_t events_,