Auto merge of #3546 - matthiaskrgr:fix_install, r=oli-obk
Revert "Merge pull request #3257 from o01eg/remove-sysroot"
This reverts commit 041c49c1ed11b016d6ab9379643bb1da2adf5bfe, reversing
changes made to 1df5766cbb559aab0ad5c2296d8b768182b5186c.
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