rustdoc: Private structs implementing public traits are visible as dangling links

[nodakai]

Seeing is believing: http://doc.rust-lang.org/std/ops/trait.Drop.html

core::finally::Finallyalizer and collections::vec::PartialVecNonZeroSized are two of many dangling links in the Drop page. They shouldn't be visible at all because core::finally and PartialVecNonZeroSized are private items.

[scialex]

I think this is because --passes strip-priv is totally broken. See #19111

[alexcrichton]

Closing as a duplicate of #14586