Fix windows failure (fixup rust-lang#22538)

Author: Manishearth

src/libstd/sys/windows/thread.rs

@@ -11,7 +11,6 @@
 use prelude::v1::*;
 
 use boxed;
-use boxed::Box;
 use cmp;
 use io;
 use mem;

src/libstd/sys/windows/thread_local.rs

@@ -12,6 +12,7 @@ use prelude::v1::*;
 
 use libc::types::os::arch::extra::{DWORD, LPVOID, BOOL};
 
+use boxed;
 use mem;
 use ptr;
 use rt;
@@ -139,7 +140,7 @@ unsafe fn init_dtors() {
         DTOR_LOCK.lock();
         let dtors = DTORS;
         DTORS = ptr::null_mut();
-        Boxed::from_raw(dtors);
+        Box::from_raw(dtors);
         assert!(DTORS.is_null()); // can't re-init after destructing
         DTOR_LOCK.unlock();
     });