Unrolled build for rust-lang#120577

Rollup merge of rust-lang#120577 - wutchzone:slice_split_at_unchecked, r=m-ou-se

Stabilize slice_split_at_unchecked

Greetings!

I took the opportunity, and I tried to stabilize the `slice_split_at_unchecked` feature. I followed the guidelines, and I hope everything was done correctly 🤞 .

Closes rust-lang#76014

library/core/src/lib.rs

@@ -190,7 +190,6 @@
 #![feature(ptr_metadata)]
 #![feature(set_ptr_value)]
 #![feature(slice_ptr_get)]
-#![feature(slice_split_at_unchecked)]
 #![feature(split_at_checked)]
 #![feature(str_internals)]
 #![feature(str_split_inclusive_remainder)]

library/core/src/slice/mod.rs

@@ -1944,8 +1944,6 @@ impl<T> [T] {
     /// # Examples
     ///
     /// ```
-    /// #![feature(slice_split_at_unchecked)]
-    ///
     /// let v = [1, 2, 3, 4, 5, 6];
     ///
     /// unsafe {
@@ -1966,7 +1964,7 @@ impl<T> [T] {
     ///     assert_eq!(right, []);
     /// }
     /// ```
-    #[unstable(feature = "slice_split_at_unchecked", reason = "new API", issue = "76014")]
+    #[stable(feature = "slice_split_at_unchecked", since = "CURRENT_RUSTC_VERSION")]
     #[rustc_const_stable(feature = "const_slice_split_at_unchecked", since = "1.77.0")]
     #[inline]
     #[must_use]
@@ -2008,8 +2006,6 @@ impl<T> [T] {
     /// # Examples
     ///
     /// ```
-    /// #![feature(slice_split_at_unchecked)]
-    ///
     /// let mut v = [1, 0, 3, 0, 5, 6];
     /// // scoped to restrict the lifetime of the borrows
     /// unsafe {
@@ -2021,7 +2017,7 @@ impl<T> [T] {
     /// }
     /// assert_eq!(v, [1, 2, 3, 4, 5, 6]);
     /// ```
-    #[unstable(feature = "slice_split_at_unchecked", reason = "new API", issue = "76014")]
+    #[stable(feature = "slice_split_at_unchecked", since = "CURRENT_RUSTC_VERSION")]
     #[rustc_const_unstable(feature = "const_slice_split_at_mut", issue = "101804")]
     #[inline]
     #[must_use]