Remove unnecessary call to call_with_pp_support_hir.

The callback is trivial and no pp support is actually needed. This makes
the `HirTree` case more like the `AstTree` case above.

compiler/rustc_driver_impl/src/pretty.rs

@@ -441,10 +441,8 @@ pub fn print_after_hir_lowering<'tcx>(tcx: TyCtxt<'tcx>, ppm: PpMode) {
         }),
 
         HirTree => {
-            call_with_pp_support_hir(&PpHirMode::Normal, tcx, move |_annotation, hir_map| {
-                debug!("pretty printing HIR tree");
-                format!("{:#?}", hir_map.krate())
-            })
+            debug!("pretty printing HIR tree");
+            format!("{:#?}", tcx.hir().krate())
         }
 
         _ => unreachable!(),