rollup merge of #21340: pshc/libsyntax-no-more-ints

Collaboration with @rylev!

I didn't change `int` in the [quasi-quoter](99ae1a30f3/src/libsyntax/ext/quote.rs (L328)), because I'm not sure if there will be adverse effects.

Addresses #21095.

src/libsyntax/test.rs

@@ -339,8 +339,8 @@ fn is_bench_fn(cx: &TestCtxt, i: &ast::Item) -> bool {
                 let tparm_cnt = generics.ty_params.len();
                 // NB: inadequate check, but we're running
                 // well before resolve, can't get too deep.
-                input_cnt == 1u
-                    && no_output && tparm_cnt == 0u
+                input_cnt == 1us
+                    && no_output && tparm_cnt == 0us
             }
           _ => false
         }