`is_aligned` goes wrong on non-provenance pointers with symbolic alignment

[RalfJung]

The following should pass even with symbolic alignment checks:

#![feature(strict_provenance, pointer_is_aligned)]

use std::ptr;

fn main() {
    let p = ptr::invalid::<()>(1);
    assert!(p.is_aligned());
}

However, the assertion fails. This is almost certainly caused by rust-lang/rust#102795.