[NaCl SDK] Fix SDK waterfall: unistd.h does not exist on windows.

native_client_sdk/src/libraries/nacl_io/kernel_handle.cc

 /* Copyright (c) 2012 The Chromium Authors. All rights reserved.
  * Use of this source code is governed by a BSD-style license that can be
  * found in the LICENSE file.
  */
 #include "nacl_io/kernel_handle.h"
 
 #include <errno.h>
 #include <fcntl.h>
 #include <pthread.h>
 
-#ifndef WIN32
-// Needed for SEEK_SET/SEEK_CUR/SEEK_END.
-#include <unistd.h>
-#endif
-
 #include "nacl_io/mount.h"
 #include "nacl_io/mount_node.h"
+#include "nacl_io/osunistd.h"
 
 // It is only legal to construct a handle while the kernel lock is held.
 KernelHandle::KernelHandle(Mount* mnt, MountNode* node)
     : mount_(mnt), node_(node), offs_(0) {}
 
 Error KernelHandle::Init(int open_mode) {
   if (open_mode & O_APPEND) {
     size_t node_size;
     Error error = node_->GetSize(&offs_);
     if (error)
@@ skipping 36 matching lines @@
   // end and the new end.
   if (new_offset > node_size) {
     error = node_->FTruncate(new_offset);
     if (error)
       return EINVAL;
   }
 
   *out_offset = offs_ = new_offset;
   return 0;
 }