SMP - Single shot local timer

- APIC timer always reprogrammed if expired

- timer tick never happens when in kernel => never immediate return
  from userspace to kernel because of a buffered interrupt

- renamed argument to lapic_set_timer_one_shot()

- removed arch_ prefix from timer functions

kernel/main.c

@@ -376,8 +376,8 @@ PUBLIC void minix_shutdown(timer_t *tp)
   if (ncpus > 1)
 	  smp_shutdown_aps();
 #endif
-  arch_stop_local_timer();
   hw_intr_disable_all();
+  stop_local_timer();
   intr_init(INTS_ORIG, 0);
   arch_shutdown(tp ? tmr_arg(tp)->ta_int : RBT_PANIC);
 }