libextra: Rename the actual metadata names of libcore to libstd and libstd to libextra

src/libsyntax/ext/asm.rs

@@ -12,6 +12,8 @@
  * Inline assembly support.
  */
 
+use core::prelude::*;
+
 use ast;
 use codemap::span;
 use ext::base;