Auto merge of #60874 - ehuss:update-cargo, r=alexcrichton

Update cargo

17 commits in 759b6161a328db1d4863139e90875308ecd25a75..c4fcfb725b4be00c72eb9cf30c7d8b095577c280
2019-05-06 20:47:49 +0000 to 2019-05-15 19:48:47 +0000
- tests: registry: revert readonly permission after running tests. (rust-lang/cargo#6947)
- Remove Candidate (rust-lang/cargo#6946)
- Fix for "Running cargo update without a Cargo.lock ignores arguments" rust-lang/cargo#6872 (rust-lang/cargo#6904)
- Fix a minor mistake in the changelog. (rust-lang/cargo#6944)
- Give a better error message when crates.io requests time out (rust-lang/cargo#6936)
- Re-enable compatibility with readonly CARGO_HOME (rust-lang/cargo#6940)
- Fix version of `ignore`. (rust-lang/cargo#6938)
- Stabilize offline mode. (rust-lang/cargo#6934)
- zsh: Add doc options to include non-public items documentation (rust-lang/cargo#6929)
- zsh: Suggest --lib option as binary template now the default (rust-lang/cargo#6926)
- Migrate package include/exclude to gitignore patterns. (rust-lang/cargo#6924)
- Implement the Cargo half of pipelined compilation (take 2) (rust-lang/cargo#6883)
- Always include `Cargo.toml` when packaging. (rust-lang/cargo#6925)
- Remove unnecessary calls to masquerade_as_nightly_cargo. (rust-lang/cargo#6923)
- download: fix "Downloaded 1 crates" message (crates -> crate) (rust-lang/cargo#6920)
- Changed RUST_LOG usage to CARGO_LOG to avoid confusion. (rust-lang/cargo#6918)
- crate download: don't print that a crate was the largest download if it was the only download (rust-lang/cargo#6916)