Updated E0071 to new format.

The span underlines only the name of the thing that's not a struct rather
than the whole expression.

src/test/compile-fail/trait-as-struct-constructor.rs

@@ -13,4 +13,5 @@ trait TraitNotAStruct {}
 fn main() {
     TraitNotAStruct{ value: 0 };
     //~^ ERROR: `TraitNotAStruct` does not name a struct or a struct variant [E0071]
+    //~| NOTE not a struct
 }