Rollup of 6 pull requests

[frewsxcv]

• Successful merges: Add a way to get shorter spans until char for pointing at defs #41214, Run tests for the cargo submodule in tree #41362, Bump stage0 to fix ARM LLVM #41369, Fix ICE building gluon_vm #41377, rustc_trans: do not treat byval as using up registers. #41378, Override ToOwned::clone_into for Path and OsStr #41390
• Failed merges: Expanded docs and examples for PathBuf::file_name and friends #41376

[rust-highfive]

Thanks for the pull request, and welcome! The Rust team is excited to review your changes, and you should hear from @arielb1 (or someone else) soon.

If any changes to this PR are deemed necessary, please add them as extra commits. This ensures that the reviewer can see what has changed since they last reviewed the code. Due to the way GitHub handles out-of-date commits, this should also make it reasonably obvious what issues have or haven't been addressed. Large or tricky changes may require several passes of review and changes.

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[frewsxcv]

@bors r+ p=10

[bors]

📌 Commit b3fea92 has been approved by frewsxcv

[bors]

⌛ Testing commit b3fea92 with merge b463db0...

[bors]

💔 Test failed - status-travis