Remove ordinalize.

Some minor (English only) heroics are performed to print error messages
like "5th rule of macro `m` is never used". The form "rule #5 of macro
`m` is never used" is just as good and much simpler to implement.

compiler/rustc_resolve/src/macros.rs

@@ -327,11 +327,7 @@ impl<'a, 'tcx> ResolverExpand for Resolver<'a, 'tcx> {
                 UNUSED_MACRO_RULES,
                 node_id,
                 rule_span,
-                format!(
-                    "{} rule of macro `{}` is never used",
-                    crate::diagnostics::ordinalize(arm_i + 1),
-                    ident.name
-                ),
+                format!("rule #{} of macro `{}` is never used", arm_i + 1, ident.name),
             );
         }
     }