Revert "Merge pull request #3257 from o01eg/remove-sysroot"

[matthiaskrgr]

This reverts commit 041c49c, reversing
changes made to 1df5766.

The PR broke running a cargo-install'd clippy.
The installed clippy would not be able to find a crate for std.

Fixes #3523
Reopens #2874

[oli-obk]

I'd rather not revert but find a way to make it work. Can we implement this in cargo-clippy instead of clippy-driver?

[matthiaskrgr]

Well I'd still like to have this reverted until an actual fix is established since this might break CI for people who install the git version on travois (which we advertised in README.md).

[oli-obk]

which we advertised in README.md

We did, we don't anymore. Using the git version is suboptimal for everyone as you have nearly no chance of figuring out the correct version.

We can add instructions for compiling clippy and manually copying the binaries into the correct location so it works again.

[matthiaskrgr]

I can't even call the clippy binary manually after compiling it (like ./target/debug/cargo-clippy), it's hard to believe that this slipped through CI...

Can we apply the revert until the bug has been fixed?

[oli-obk]

@bors r+

We should focus on rust-lang/cargo#6356 to solve this correctly

[bors]

📌 Commit 9fb8022 has been approved by oli-obk

[bors]

⌛ Testing commit 9fb8022 with merge 980bcd8...

[bors]

☀️ Test successful - status-appveyor, status-travis
Approved by: oli-obk
Pushing 980bcd8 to master...