Auto merge of #81756 - ehuss:update-cargo, r=ehuss

Auto merge of #81756 - ehuss:update-cargo, r=ehuss

Update cargo

5 commits in e099df243bb2495b9b197f79c19f124032b1e778..34170fcd6e0947808a1ac63ac85ffc0da7dace2f
2021-02-01 16:24:34 +0000 to 2021-02-04 15:52:52 +0000
- Fix permission issue with `cargo vendor`. (rust-lang/cargo#9131)
- Add split-debuginfo profile option (rust-lang/cargo#9112)
- Add RegistryBuilder for tests, and update crates-io error handling. (rust-lang/cargo#9126)
- Add some documentation for index and registry stuff. (rust-lang/cargo#9125)
- Fix env/cfg set for `cargo test` and `cargo run`. (rust-lang/cargo#9122)