slice indexing broken

[oli-obk]

The following piece of code triggers this assertion

#[miri_run]
fn slice() -> u8 {
    let arr: &[_] = &[101, 102, 103, 104, 105, 106];
    arr[5]
}

[solson]

Lvalue handling in general needs an overhaul. I'll try to clean it up and fix this at the same time (though the fix for this could be trivial).

[solson]

I fixed this in my new-data-layout branch, which I'll merge into master once it passes all tests.