refactor trans into trans_closure; restore original closure repr

Author: nikomatsakis

src/comp/back/abi.rs

@@ -74,8 +74,8 @@ const fn_field_box: int = 1;
 
 const closure_elt_tydesc: int = 0;
 const closure_elt_bindings: int = 1;
-const closure_elt_n_ty_params: int = 2;
-const closure_elt_ty_params: int = 3;
+//const closure_elt_n_ty_params: int = 2;
+const closure_elt_ty_params: int = 2; // 3;
 
 const vec_elt_fill: int = 0;