should check crossing C boudary from resume

mrbgems/mruby-fiber/src/fiber.c

@@ -154,7 +154,13 @@ fiber_resume(mrb_state *mrb, mrb_value self)
   struct mrb_context *c = fiber_check(mrb, self);
   mrb_value *a;
   int len;
+  mrb_callinfo *ci;
 
+  for (ci = c->ci; ci >= c->cibase; ci--) {
+    if (ci->acc < 0) {
+      mrb_raise(mrb, E_ARGUMENT_ERROR, "can't cross C function boundary");
+    }
+  }
   if (c->status == MRB_FIBER_RESUMED) {
     mrb_raise(mrb, E_RUNTIME_ERROR, "double resume");
   }