Rollup merge of #89507 - lopopolo:lopopolo/ordering-repr-i8, r=joshtriplett

Add `#[repr(i8)]` to `Ordering`

Followup to #89491 to allow `Ordering` to auto-derive `AsRepr` once the proposal to add `AsRepr` (#81642) lands.

cc ``@joshtriplett``

Author: JohnTitor

library/core/src/cmp.rs

@@ -323,6 +323,7 @@ pub struct AssertParamIsEq<T: Eq + ?Sized> {
 /// ```
 #[derive(Clone, Copy, PartialEq, Debug, Hash)]
 #[stable(feature = "rust1", since = "1.0.0")]
+#[repr(i8)]
 pub enum Ordering {
     /// An ordering where a compared value is less than another.
     #[stable(feature = "rust1", since = "1.0.0")]