Merge from rustc

Author: The Miri Conjob Bot

crates/hir-def/src/attr/builtin.rs

@@ -262,24 +262,6 @@ pub const INERT_ATTRIBUTES: &[BuiltinAttribute] = &[
         naked_functions, experimental!(naked)
     ),
 
-    // Plugins:
-    // BuiltinAttribute {
-    //     name: sym::plugin,
-    //     only_local: false,
-    //     type_: CrateLevel,
-    //     template: template!(List: "name"),
-    //     duplicates: DuplicatesOk,
-    //     gate: Gated(
-    //         Stability::Deprecated(
-    //             "https://github.com/rust-lang/rust/pull/64675",
-    //             Some("may be removed in a future compiler version"),
-    //         ),
-    //         sym::plugin,
-    //         "compiler plugins are deprecated",
-    //         cfg_fn!(plugin)
-    //     ),
-    // },
-
     // Testing:
     gated!(
         test_runner, CrateLevel, template!(List: "path"), ErrorFollowing, custom_test_frameworks,