rustup and update test

Author: RalfJung

rust-version

@@ -1 +1 @@
-89631663b7ad2d46d3e4f52bcfa7bee2be9eb82b
+cf9cf7c923eb01146971429044f216a3ca905e06

tests/run-pass/concurrency/sync_singlethread.rs

@@ -1,5 +1,3 @@
-#![feature(rustc_private, renamed_spin_loop)]
-
 use std::sync::{Mutex, TryLockError};
 use std::sync::atomic;
 use std::hint;