the never type got de-stabilized again; adjust tests

rust-version

@@ -1 +1 @@
-12307b3b08edee543a78fb9d4a837fbd6d6ac0fa
+a605441e049f0b6d5f7715b94b8ac4662fd7fcf6

tests/compile-fail/never_say_never.rs

@@ -1,6 +1,7 @@
 // This should fail even without validation
 // compile-flags: -Zmiri-disable-validation
 
+#![feature(never_type)]
 #![allow(unreachable_code)]
 
 fn main() {

tests/compile-fail/never_transmute_humans.rs

@@ -1,6 +1,8 @@
 // This should fail even without validation
 // compile-flags: -Zmiri-disable-validation
 
+#![feature(never_type)]
+
 struct Human;
 
 fn main() {

tests/compile-fail/never_transmute_void.rs

@@ -1,6 +1,7 @@
 // This should fail even without validation
 // compile-flags: -Zmiri-disable-validation
 
+#![feature(never_type)]
 #![allow(unused, invalid_value)]
 
 enum Void {}

tests/run-pass/async-fn.rs

@@ -1,3 +1,5 @@
+#![feature(never_type)]
+
 use std::{future::Future, pin::Pin, task::Poll, ptr};
 use std::task::{Waker, RawWaker, RawWakerVTable, Context};
 

tests/run-pass/generator.rs

@@ -1,4 +1,4 @@
-#![feature(generators, generator_trait)]
+#![feature(generators, generator_trait, never_type)]
 
 use std::ops::{GeneratorState, Generator};
 use std::pin::Pin;

tests/run-pass/loop-break-value.rs

@@ -1,3 +1,4 @@
+#![feature(never_type)]
 #![allow(unreachable_code)]
 
 #[allow(unused)]

tests/run-pass/panic/catch_panic.rs

@@ -1,6 +1,6 @@
 // ignore-windows: Unwind panicking does not currently work on Windows
+#![feature(never_type)]
 #![allow(const_err)]
-
 use std::panic::{catch_unwind, AssertUnwindSafe};
 use std::cell::Cell;