Rollup of 5 pull requests

[frewsxcv]

• Successful merges: Correcting mistakes in the README.md #40797, Use 64 bits emulator to run android tests #40971, cstore: return an immutable borrow from visible_parent_map #41061, Re-enable appveyor cache #41075, Remove some CStr transmutes. #41120
• Failed merges:

[rust-highfive]

Thanks for the pull request, and welcome! The Rust team is excited to review your changes, and you should hear from @nikomatsakis (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 Due to the way GitHub handles out-of-date commits, this should also make it reasonably obvious what issues have or haven't been addressed.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.

Please see the contribution instructions for more information.

[frewsxcv]

@bors r+ p=10

[bors]

📌 Commit 201bb1e has been approved by frewsxcv

[bors]

⌛ Testing commit 201bb1e with merge b94ba43...

[bors]

💔 Test failed - status-travis