Merge dead bb pruning and unreachable bb deduplication.

compiler/rustc_mir_transform/src/deduplicate_blocks.rs

@@ -25,7 +25,7 @@ impl<'tcx> MirPass<'tcx> for DeduplicateBlocks {
         if has_opts_to_apply {
             let mut opt_applier = OptApplier { tcx, duplicates };
             opt_applier.visit_body(body);
-            simplify_cfg(tcx, body);
+            simplify_cfg(body);
         }
     }
 }