ices/71212.rs: fixed with errors

[github-actions]

Issue: rust-lang/rust#71212

#![feature(const_mut_refs)]

const FOO: &mut i32 = &mut 4;

fn main() {
    *FOO = 2;
}

=== stdout ===
=== stderr ===
error: mutable memory (`&mut`) is not allowed in constant
 --> /home/runner/work/glacier/glacier/ices/71212.rs:3:1
  |
3 | const FOO: &mut i32 = &mut 4;
  | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^

error: aborting due to previous error

==============

[JohnTitor]

This is as well.