Rollup merge of rust-lang#76172 - ecstatic-morse:revert-75463, r=RalfJung

Revert rust-lang#75463

This was approved by me prematurely. It needs T-libs approval. Sorry @CDirkx.

r? @RalfJung

Author: tmandry

library/core/src/cmp.rs

@@ -356,9 +356,8 @@ impl Ordering {
     /// ```
     #[inline]
     #[must_use]
-    #[rustc_const_stable(feature = "const_ordering", since = "1.48.0")]
     #[stable(feature = "rust1", since = "1.0.0")]
-    pub const fn reverse(self) -> Ordering {
+    pub fn reverse(self) -> Ordering {
         match self {
             Less => Greater,
             Equal => Equal,
@@ -395,9 +394,8 @@ impl Ordering {
     /// ```
     #[inline]
     #[must_use]
-    #[rustc_const_stable(feature = "const_ordering", since = "1.48.0")]
     #[stable(feature = "ordering_chaining", since = "1.17.0")]
-    pub const fn then(self, other: Ordering) -> Ordering {
+    pub fn then(self, other: Ordering) -> Ordering {
         match self {
             Equal => other,
             _ => self,