Rollup merge of #121377 - pitaj:lazy_cell_fn_pointer, r=dtolnay

Stabilize `LazyCell` and `LazyLock`

Closes #109736

This stabilizes the [`LazyLock`](https://doc.rust-lang.org/stable/std/sync/struct.LazyLock.html) and [`LazyCell`](https://doc.rust-lang.org/stable/std/cell/struct.LazyCell.html) types:

```rust
static HASHMAP: LazyLock<HashMap<i32, String>> = LazyLock::new(|| {
    println!("initializing");
    let mut m = HashMap::new();
    m.insert(13, "Spica".to_string());
    m.insert(74, "Hoyten".to_string());
    m
});

let lazy: LazyCell<i32> = LazyCell::new(|| {
    println!("initializing");
    92
});
```

r? libs-api

0 files changed, 0 insertions, 0 deletions