Retagging: do not retag 'raw reborrows' When doing `&raw const (*raw_ptr).field`, we do not want any retagging; the original provenance should be fully preserved. Fixes https://github.com/rust-lang/miri/issues/1608 Test added by https://github.com/rust-lang/miri/pull/1614 Not sure whom to ask for review on this... `@oli-obk` can you have a look? Or maybe highfive makes a good choice.^^