#ifdef LISP_FEATURE_SB_THREAD
extern void interrupt_thread_handler(int, siginfo_t*, void*);
extern void sig_stop_for_gc_handler(int, siginfo_t*, void*);
-extern void thread_exit_handler(int, siginfo_t*, void*);
#endif
extern void undoably_install_low_level_interrupt_handler (int signal,
void