use idle (#1039)

parallel-rdp/interface.hpp

@@ -58,6 +58,7 @@ void rdp_update_screen();
 void rdp_render_frame();
 CALL_BACK rdp_check_callback();
 uint64_t rdp_process_commands();
+void rdp_idle();
 void rdp_onscreen_message(const char *message, MESSAGE_LENGTH milliseconds);
 void rdp_check_framebuffers(uint32_t address, uint32_t length);
 size_t rdp_state_size();