message: test: revive nightly plugin tests to work
diff: @@ -361,6 +361,7 @@ fn panic_abort_plugins() {
  r#"
  #![feature(rustc_private)]
  extern crate rustc_ast;
  + extern crate rustc_driver;
  "#,
  )
  .build();
  @@ -408,6 +409,7 @@ fn shared_panic_abort_plugins() {
  r#"
  #![feature(rustc_private)]
  extern crate rustc_ast;
  + extern crate rustc_driver;
  extern crate baz;
  "#,
  )
  