87/11: Fix argument of exit

Author: michael-schwarz

tests/regression/87-once/11-combination.c

@@ -21,7 +21,7 @@ void* thread(void* arg) {
     // Also showing that g is not NULL here requires "Extended Support for pthread once" as explained in appendix C.
     // It was added manually here so we can show off that at the end we can exclude the in initial value even
     // though main didn't write
-    exit();
+    exit(42);
   }
   *g = 4711; //NORACE
   pthread_mutex_unlock(&mtx);