auto merge of #11930 : bjz/rust/next_power_of_two, r=huonw

diff --cc src/libarena/lib.rs
index 44ec3f4a5a1d79df93c94a81511fdb7022d96fe7,c4fc2819155838b74f8c4c704ba89bf54f8dd515..ac290de0d72188ff8d7db6e7054275e35df95837
--- 1/src/libarena/lib.rs
--- 2/src/libarena/lib.rs
+++ b/src/libarena/lib.rs
@@@ -33,10 -33,8 +33,9 @@@ use std::cast
  use std::cell::{Cell, RefCell};
  use std::num;
  use std::ptr;
 +use std::kinds::marker;
  use std::mem;
  use std::rt::global_heap;
- use std::uint;
  use std::unstable::intrinsics::{TyDesc, get_tydesc};
  use std::unstable::intrinsics;
  use std::util;

diff --cc src/libstd/str.rs
Simple merge

diff --cc src/libstd/vec.rs
Simple merge