Rollup merge of #108549 - clubby789:fix-link-cfg-issue, r=eholk

Remove issue number for `link_cfg`

Fixes #72059

Per #37406 and its [unstable book entry](https://doc.rust-lang.org/beta/unstable-book/language-features/link-cfg.html), this is an internal feature, and therefore perma-unstable and not being tracked

Author: matthiaskrgr