Fix function prototype warnings for C23 compatibility

- Add proper function prototypes: fatal(), my_exit(), set_order()
- Fix function pointer types to match call sites: void (*func)(int)
- Remove conflicting localtime() declaration in rip.c
- Fix incorrect new_item() call in state.c (remove unused argument)

Result: Zero compilation warnings, C23 compatible.

See MODERNIZATION_LOG.md for detailed analysis.

state.c

@@ -1413,7 +1413,7 @@ rs_read_object_list(FILE *inf, THING **list)
 
     for (i = 0; i < cnt; i++) 
     {
-        l = new_item(sizeof(THING));
+        l = new_item();
 
         memset(l,0,sizeof(THING));