Rollup merge of #143059 - jieyouxu:slice-as-chunks, r=cuviper

Fix 1.88 relnotes

- Use stable std links for `impl Default for {*const,*mut} T`
- Add missing relnotes for https://github.com/rust-lang/rust/pull/139656
    ```rs
    impl [T] {
        const fn as_chunks<const N: usize>(&self) -> (&[[T; N]], &[T]);
        const fn as_rchunks<const N: usize>(&self) -> (&[T], &[[T; N]]);
        const unsafe fn as_chunks_unchecked<const N: usize>(&self) -> &[[T; N]];
        const fn as_chunks_mut<const N: usize>(&mut self) -> (&mut [[T; N]], &mut [T]);
        const fn as_rchunks_mut<const N: usize>(&mut self) -> (&mut [T], &mut [[T; N]]);
        const unsafe fn as_chunks_unchecked_mut<const N: usize>(&mut self) -> &mut [[T; N]];
    }
    ```
- Add missing `mod ffi::c_str` and `hint::select_unpredictable`

r? `@cuviper`