panic when comparing arrays where one of them has a validity bitmap + offset

[ritchie46]

Since #540 the following code panics.

use arrow::array::*;
use arrow::datatypes::{DataType, Field};
use arrow::bitmap::Bitmap;
use std::iter::FromIterator;
use std::sync::Arc;
use arrow::compute::comparison::{compare, Operator};

fn main() {
    // create a list-array
    let offsets = vec![0, 2, 3];
    let validity = Bitmap::from_iter([true, true].iter().copied());

    let values = vec![None, Some(1), Some(2), Some(3), Some(4)];
    let values = Arc::new(PrimitiveArray::from_iter(values.iter().copied()));

    let list_arr = ListArray::from_data(DataType::List(Box::new(Field::new("", DataType::Int32, true))), offsets.into(), values, Some(validity));

    // get a value from the list-array
    let sublist = list_arr.value(1);

    // compare that value with another array that not has an offset.
    let values = vec![2];
    let values = Arc::new(PrimitiveArray::from_iter(values.iter().copied().map(Some)));

    compare(&*sublist, &*values, Operator::Eq);
}

thread 'main' panicked at 'validity's bitmap offset must equal values offset', /home/ritchie46/.cargo/git/checkouts/arrow2-8a2ad61d97265680/4491954/src/array/boolean/mod.rs:49:13
note: run with `RUST_BACKTRACE=1` environment variable to display a backtrace

[ritchie46]

Fixed/ delayed by #552