Rollup merge of #138084 - nnethercote:workspace-lints, r=jieyouxu

Use workspace lints for crates in `compiler/`

This is nicer and hopefully less error prone than specifying lints via bootstrap.

r? ``@jieyouxu``

compiler/rustc_lint_defs/Cargo.toml

@@ -15,3 +15,6 @@ rustc_serialize = { path = "../rustc_serialize" }
 rustc_span = { path = "../rustc_span" }
 serde = { version = "1.0.125", features = ["derive"] }
 # tidy-alphabetical-end
+
+[lints]
+workspace = true

compiler/rustc_lint_defs/src/lib.rs

@@ -1,7 +1,3 @@
-// tidy-alphabetical-start
-#![warn(unreachable_pub)]
-// tidy-alphabetical-end
-
 use rustc_abi::ExternAbi;
 use rustc_ast::AttrId;
 use rustc_ast::attr::AttributeExt;