- Add clippy_dev to the rust workspace
Before, it would give an error that it wasn't either included or
excluded from the workspace:
```
error: current package believes it's in a workspace when it's not:
current: /home/joshua/rustc/src/tools/clippy/clippy_dev/Cargo.toml
workspace: /home/joshua/rustc/Cargo.toml
this may be fixable by adding `src/tools/clippy/clippy_dev` to the `workspace.members` array of the manifest located at: /home/joshua/rustc/Cargo.toml
Alternatively, to keep it out of the workspace, add the package to the `workspace.exclude` array, or add an empty `[workspace]` table to the package's manifest.
```
- Change clippy's copy of compiletest not to special-case
rust-lang/rust. Using OUT_DIR confused `clippy_dev` and it couldn't find
the test outputs. This is one of the reasons why `cargo dev bless` used
to silently do nothing (the others were that `CARGO_TARGET_DIR` and
`PROFILE` weren't set appropriately).
- Run clippy_dev on test failure
I tested this by removing a couple lines from a stderr file, and they
were correctly replaced.
- Fix clippy_dev warnings
