Rollup merge of #129648 - nnethercote:unreachable_pub-2, r=Urgau

More `unreachable_pub`

Add `unreachable_pub` checking to some more compiler crates. A follow-up to #126013.

r? ``@Urgau``

compiler/rustc_driver_impl/src/lib.rs

@@ -16,6 +16,7 @@
 #![feature(panic_update_hook)]
 #![feature(result_flattening)]
 #![feature(rustdoc_internals)]
+#![warn(unreachable_pub)]
 // tidy-alphabetical-end
 
 use std::cmp::max;