fix incorrect param env in dead code lint

Author: beepster4096

core/tests/mem.rs

@@ -458,4 +458,4 @@ fn offset_of_addr() {
     assert_eq!(ptr::addr_of!(base).addr() + offset_of!(Foo, y), ptr::addr_of!(base.y).addr());
     assert_eq!(ptr::addr_of!(base).addr() + offset_of!(Foo, z.0), ptr::addr_of!(base.z.0).addr());
     assert_eq!(ptr::addr_of!(base).addr() + offset_of!(Foo, z.1), ptr::addr_of!(base.z.1).addr());
-}
+}