adjust dangling-int-ptr error message based on suggestions by `@saethlin` in https://github.com/rust-lang/miri/issues/2163 Fixes https://github.com/rust-lang/miri/issues/2163 I also did a bit of refactoring on this, so we have a helper method to create a `Pointer` with `None` provenance.
For more information about how rustc works, see the rustc dev guide.