message: add place holder for thread_atexit
diff: @@ -159,3 +159,9 @@ pub extern "C" fn sys_join(id: Tid) -> i32 {
  _ => -EINVAL
  }
  }
  +
  +#[no_mangle]
  +pub extern "C" fn __thread_atexit(dtor: unsafe extern fn(*mut u8), arg: *mut u8) -> i32 {
  + info!("thread_atexit: dtor 0x{:x}, arg 0x{:x}", dtor as *const u8 as usize, arg as *const u8 as usize);
  + 0
  +}
  