Implement x.py test src/tools/clippy --bless

- 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

clippy_dev/src/new_lint.rs

@@ -44,7 +44,7 @@ pub fn create(pass: Option<&str>, lint_name: Option<&str>, category: Option<&str
     create_test(&lint).context("Unable to create a test for the new lint")
 }
 
-fn create_lint(lint: &LintData) -> io::Result<()> {
+fn create_lint(lint: &LintData<'_>) -> io::Result<()> {
     let (pass_type, pass_lifetimes, pass_import, context_import) = match lint.pass {
         "early" => ("EarlyLintPass", "", "use rustc_ast::ast::*;", "EarlyContext"),
         "late" => ("LateLintPass", "<'_>", "use rustc_hir::*;", "LateContext"),
@@ -68,7 +68,7 @@ fn create_lint(lint: &LintData) -> io::Result<()> {
     write_file(lint.project_root.join(&lint_path), lint_contents.as_bytes())
 }
 
-fn create_test(lint: &LintData) -> io::Result<()> {
+fn create_test(lint: &LintData<'_>) -> io::Result<()> {
     fn create_project_layout<P: Into<PathBuf>>(lint_name: &str, location: P, case: &str, hint: &str) -> io::Result<()> {
         let mut path = location.into().join(case);
         fs::create_dir(&path)?;

tests/compile-test.rs

@@ -83,14 +83,7 @@ fn default_config() -> compiletest::Config {
         third_party_crates(),
     ));
 
-    config.build_base = if cargo::is_rustc_test_suite() {
-        // This make the stderr files go to clippy OUT_DIR on rustc repo build dir
-        let mut path = PathBuf::from(env!("OUT_DIR"));
-        path.push("test_build_base");
-        path
-    } else {
-        host_lib().join("test_build_base")
-    };
+    config.build_base = host_lib().join("test_build_base");
     config.rustc_path = clippy_driver_path();
     config
 }