Problem: IO thread name uses space separator, the rest uses /

Solution: use / like the rest of the names

src/io_thread.cpp

@@ -57,7 +57,8 @@ zmq::io_thread_t::~io_thread_t ()
 void zmq::io_thread_t::start ()
 {
     char name[16];
-    snprintf(name, sizeof(name), "IO %u", get_tid() - zmq::ctx_t::reaper_tid);
+    snprintf (name, sizeof (name), "IO/%u",
+              get_tid () - zmq::ctx_t::reaper_tid);
     //  Start the underlying I/O thread.
     _poller->start (name);
 }