Rollup merge of #54904 - Kerollmops:stabilize-option-replace, r=Centril

Fixes #47311.
r? @nrc

src/libcore/option.rs

@@ -867,8 +867,6 @@ impl<T> Option<T> {
     /// # Examples
     ///
     /// ```
-    /// #![feature(option_replace)]
-    ///
     /// let mut x = Some(2);
     /// let old = x.replace(5);
     /// assert_eq!(x, Some(5));
@@ -880,7 +878,7 @@ impl<T> Option<T> {
     /// assert_eq!(old, None);
     /// ```
     #[inline]
-    #[unstable(feature = "option_replace", issue = "51998")]
+    #[stable(feature = "option_replace", since = "1.31.0")]
     pub fn replace(&mut self, value: T) -> Option<T> {
         mem::replace(self, Some(value))
     }

src/libcore/tests/lib.rs

@@ -39,7 +39,6 @@
 #![feature(reverse_bits)]
 #![feature(inner_deref)]
 #![feature(slice_internals)]
-#![feature(option_replace)]
 #![feature(slice_partition_dedup)]
 #![feature(copy_within)]
 

src/librustc_driver/lib.rs

@@ -21,7 +21,6 @@
 #![feature(box_syntax)]
 #![cfg_attr(unix, feature(libc))]
 #![feature(nll)]
-#![feature(option_replace)]
 #![feature(quote)]
 #![feature(rustc_diagnostic_macros)]
 #![feature(slice_sort_by_cached_key)]