Failure to infer that `ctpop(y) == 1` implies `y != 0`

If `y.is_power_of_two()` is `true`, then `y` cannot be `0`, so the `panic` branch should be eliminated

https://godbolt.org/z/q9jhsnqs7
```rust
pub fn div(x: u32, y: u32) -> u32 {
    if y.is_power_of_two() {
        x / y
    } else {
        0
    }
}

pub fn rem(x: u32, y: u32) -> u32 {
    if y.is_power_of_two() {
        x % y
    } else {
        0
    }
}
```