Missed bounds check elimination

On Rust 1.79.0.

```rust
pub const fn missing_bce(v: &[u32]) -> u32 {
    if v.is_empty() {
        return 0;
    }
    let mut sum = 0;
    let mut i = v.len() - 1;
    while i > 0 {
        sum += v[i];
        i -= 1;
    }
    sum
}
```

https://godbolt.org/z/xxjKd5anW

The compiler should be able to elide the bounds check for `v[i]` since `i` is always in [0, v.len()-1].