message: revise code to support "edition 2018"
diff: @@ -120,7 +120,7 @@ pub fn init() {
  let size = 2 * LargePageSize::SIZE;
  unsafe {
  let start = allocate(size, true);
  - ::ALLOCATOR.lock().init(start, size);
  + crate::ALLOCATOR.lock().init(start, size);
  }
  info!("Kernel heap size: {} MB", size >> 20);
  