Use localdefid index in mir encoding

Author: pierwill

compiler/rustc_metadata/src/rmeta/encoder.rs

@@ -1300,7 +1300,7 @@ impl EncodeContext<'a, 'tcx> {
             })
             .collect::<Vec<_>>();
         // Sort everything to ensure a stable order for diagnotics.
-        keys_and_jobs.sort_by_key(|&(def_id, _, _)| def_id);
+        keys_and_jobs.sort_by_key(|&(def_id, _, _)| def_id.index());
         for (def_id, encode_const, encode_opt) in keys_and_jobs.into_iter() {
             debug_assert!(encode_const || encode_opt);