remove warn

Author: mark-i-m

src/test/ui/macros/macro-multiple-matcher-bindings.rs

@@ -2,7 +2,6 @@
 // invocation time.
 
 #![allow(unused_macros)]
-#![warn(duplicate_matcher_binding_name)]
 
 macro_rules! foo1 {
     ($a:ident, $a:ident) => {}; //~ERROR duplicate matcher binding