Revert "rustc: Switch over to resolve3" due to Linux failures

This reverts commit 2c0aa257e2.

src/libsyntax/parse/common.rs

@@ -1,7 +1,6 @@
 import std::map::{hashmap};
 import ast_util::spanned;
 import parser::parser;
-import lexer::reader;
 
 type seq_sep = {
     sep: option<token::token>,