rustc: Eliminate metadata's dependency on util::common

Author: brson

src/rustc/metadata.rs

@@ -17,8 +17,6 @@ mod driver {
 }
 
 mod util {
-    import common = util_::common;
-    export common;
     import ppaux = util_::ppaux;
     export ppaux;
     import filesearch = util_::filesearch;

src/rustc/metadata/cstore.rs

@@ -5,7 +5,6 @@ import std::map;
 import std::map::hashmap;
 import syntax::{ast, attr};
 import syntax::ast_util::new_def_hash;
-import util::common::*;
 
 export cstore::{};
 export cnum_map;