Revert "librustc: Make unqualified identifier searches terminate at the nearest module scope. r=tjc"

This reverts commit a8d37af247.

src/libsyntax/attr.rs

@@ -10,8 +10,6 @@
 
 // Functions dealing with attributes and meta_items
 
-use core::prelude::*;
-
 use ast;
 use ast_util::{spanned, dummy_spanned};
 use attr;