Stabilize cfg_select

Author: folkertdev

patches/0027-sysroot_tests-128bit-atomic-operations.patch

@@ -17,8 +17,8 @@ index 1e336bf..35e6f54 100644
 @@ -2,4 +2,3 @@
  // tidy-alphabetical-start
 -#![cfg_attr(target_has_atomic = "128", feature(integer_atomics))]
- #![cfg_attr(test, feature(cfg_select))]
  #![feature(array_ptr_get)]
+ #![feature(array_try_from_fn)]
 diff --git a/coretests/tests/atomic.rs b/coretests/tests/atomic.rs
 index b735957..ea728b6 100644
 --- a/coretests/tests/atomic.rs