Handle built-in typenames in the resolve pass, rather than in parser

Closes #1728

Comments out a section of debuginfo.rs. This code was already broken
(only being called when --xg was passed, and only working on trivial
programs).

src/comp/syntax/ast_util.rs

@@ -31,6 +31,7 @@ fn def_id_of_def(d: def) -> def_id {
       def_native_mod(id) | def_const(id) | def_arg(id, _) | def_local(id, _) |
       def_variant(_, id) | def_ty(id) | def_ty_param(id, _) |
       def_binding(id) | def_use(id) | def_upvar(id, _, _) { id }
+      def_prim_ty(_) { fail; }
     }
 }