Stabilize Vec::leak

Author: SimonSapin

library/alloc/src/vec.rs

@@ -1510,14 +1510,12 @@ impl<T> Vec<T> {
     /// Simple usage:
     ///
     /// ```
-    /// #![feature(vec_leak)]
-    ///
     /// let x = vec![1, 2, 3];
     /// let static_ref: &'static mut [usize] = x.leak();
     /// static_ref[0] += 1;
     /// assert_eq!(static_ref, &[2, 2, 3]);
     /// ```
-    #[unstable(feature = "vec_leak", issue = "62195")]
+    #[stable(feature = "vec_leak", since = "1.47.0")]
     #[inline]
     pub fn leak<'a>(self) -> &'a mut [T]
     where