Apply dependency renamings when running rustdoc

[Nemo157]

Fixes #5792

[rust-highfive]

Thanks for the pull request, and welcome! The Rust team is excited to review your changes, and you should hear from @matklad (or someone else) soon.

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[alexcrichton]

@bors: r+

Thanks @Nemo157!

[bors]

📌 Commit a432619 has been approved by alexcrichton

[bors]

⌛ Testing commit a432619 with merge 191bfbf...

[bors]

☀️ Test successful - status-appveyor, status-travis
Approved by: alexcrichton
Pushing 191bfbf to master...