Rollup merge of #137305 - nnethercote:rustc_middle-2, r=lcnr

Tweaks in and around `rustc_middle`

A bunch of tiny improvements I found while working on bigger things.

r? ```@lcnr```

compiler/rustc_borrowck/src/polonius/dump.rs

@@ -226,7 +226,7 @@ fn emit_polonius_mir<'tcx>(
         regioncx,
         closure_region_requirements,
         borrow_set,
-        pass_where.clone(),
+        pass_where,
         out,
     )?;