The comment notes that we can't because of constness, but the recent
work by @Vexu lets us use the bitcast ty cause constness comes later.

The following tests pass from this:

```
test "A" {
    const ary = [_:0]u8{42};
    const ptr: [*:0]const u8 = &ary;
    try expect(ptr[1] == 0);
}

test "B" {
    comptime {
        const ary = [_:0]u8{42};
        const ptr: [*:0]const u8 = &ary;
        try expect(ptr[1] == 0);
    }
}
```