fix ^D exit for bitmonerod

It uses the async console handler differently than simplewallet,
and wasn't running the same exit code, causing it to never actually
exit after breaking out of the console entry loop.

src/daemon/command_server.h

@@ -62,7 +62,7 @@ public:
 
   bool process_command_vec(const std::vector<std::string>& cmd);
 
-  bool start_handling();
+  bool start_handling(std::function<void(void)> exit_handler = NULL);
 
   void stop_handling();