Auto merge of #34245 - ollie27:rustdoc_redirect_rename, r=alexcrichton

rustdoc: Fix redirect pages for renamed reexports

We need to use the name of the target not the name of the current item
when creating the link.

An example in `std` is [`std::sys::ext`](https://doc.rust-lang.org/nightly/std/sys/ext/index.html).

diff --cc src/librustdoc/html/render.rs
Simple merge