Added engine-handler parameter and a ($swap-engine-counter! <neg-fx>)

to (ikarus system $interrupts).

src/ikarus-main.c

@@ -218,7 +218,7 @@ Notice how the bsd manpages have incorrect type for the handler.
 #endif
 
 void handler(int signo, siginfo_t* info, void* uap){
-  the_pcb->engine_counter = -1;
+  the_pcb->engine_counter = fix(-1);
   the_pcb->interrupted = 1;
 }