rustc: Remove unused or seldom-used imports from middle::tstate::{bitvectors, ck}

Author: pcwalton

src/comp/middle/tstate/bitvectors.rs

@@ -3,7 +3,6 @@ import syntax::ast::*;
 import syntax::walk;
 import std::ivec;
 import std::option::*;
-import std::vec;
 import aux::constr_arg_use;
 import aux::local_node_id_to_def;
 import aux::fn_ctxt;
@@ -231,7 +230,7 @@ fn kill_poststate(&fn_ctxt fcx, node_id id, &constr_ c) -> bool {
 fn clear_in_poststate_expr(&fn_ctxt fcx, &@expr e, &poststate t) {
     alt (e.node) {
         case (expr_path(?p)) {
-            alt (vec::last(p.node.idents)) {
+            alt (std::vec::last(p.node.idents)) {
                 case (some(?i)) {
                     alt (local_node_id_to_def(fcx, e.id)) {
                         case (some(def_local(?d_id))) {

src/comp/middle/tstate/ck.rs

@@ -33,12 +33,6 @@ import tstate::ann::prestate;
 import tstate::ann::implies;
 import tstate::ann::ann_precond;
 import tstate::ann::ann_prestate;
-import std::vec::map;
-import std::vec;
-import std::vec::slice;
-import std::vec::unzip;
-import std::vec::plus_option;
-import std::vec::cat_options;
 import std::option;
 import std::option::t;
 import std::option::some;