b556398113
Target directory cleanup changelog: none * .cargo/config now has `target-dir` specified so that it is inherited by child projects. The target directory needs to be shared with clippy_dev, but not necessarily at the project root. (cc #7625) * Uses `std::env::current_exe` (and its parent directories) whenever possible * `CLIPPY_DRIVER_PATH` and `TARGET_LIBS` are no longer required from rustc bootstrap (but `HOST_LIBS` still is). These can be removed from the rustc side after merging. * `CLIPPY_DOGFOOD` and the separate target directory are removed. This was originally added to mitigate #7343. r? `@flip1995`