rustc: Use the same diagnostic emmiter for both early errors and the session

This funnels all properly reported errors through a single closure. Yay.

Author: brson

src/comp/driver/driver.rs

@@ -461,7 +461,8 @@ fn build_session(sopts: @session::options, input: str,
         sopts.target_triple,
         sopts.addl_lib_search_paths);
     let codemap = codemap::new_codemap();
-    let diagnostic_handler = diagnostic::mk_codemap_handler(codemap, none);
+    let diagnostic_handler =
+        diagnostic::mk_codemap_handler(codemap, some(demitter));
     @{targ_cfg: target_cfg,
       opts: sopts,
       cstore: cstore,