Fix the stand alone usage of the timer.

include/ascs/timer.h

@@ -195,8 +195,8 @@ protected:
 	}
 
 	void reset_io_context_refs() {if (0 == io_context_refs) add_io_context_refs(1);}
-	virtual void attach_io_context(asio::io_context& io_context_, unsigned refs) = 0;
-	virtual void detach_io_context(asio::io_context& io_context_, unsigned refs) = 0;
+	virtual void attach_io_context(asio::io_context& io_context_, unsigned refs) {}
+	virtual void detach_io_context(asio::io_context& io_context_, unsigned refs) {}
 
 private:
 	typedef std::list<timer_info> container_type;