Change the thread interface in runtime/platform and use it starting all threads

runtime/bin/thread_pool_macos.h

Index: runtime/bin/thread_pool_macos.h
diff --git a/runtime/bin/thread_pool_macos.h b/runtime/bin/thread_pool_macos.h
deleted file mode 100644
index b24a73e3283c62a26a99e0e44edb835b2a4aa008..0000000000000000000000000000000000000000
--- a/runtime/bin/thread_pool_macos.h
+++ /dev/null
@@ -1,33 +0,0 @@
-// Copyright (c) 2012, the Dart project authors.  Please see the AUTHORS file
-// for details. All rights reserved. Use of this source code is governed by a
-// BSD-style license that can be found in the LICENSE file.
-
-#ifndef BIN_THREAD_POOL_MACOS_H_
-#define BIN_THREAD_POOL_MACOS_H_
-
-#if !defined(BIN_THREAD_POOL_H_)
-#error Do not include thread_pool_macos.h directly; use thread_pool.h instead.
-#endif
-
-#include <pthread.h>
-
-#include "platform/globals.h"
-
-
-class ThreadPoolData {
- private:
-  ThreadPoolData() {}
-  ~ThreadPoolData() {}
-
-  pthread_t* threads() { return threads_; }
-  void set_threads(pthread_t* threads) { threads_ = threads; }
-
-  pthread_t* threads_;
-
-  friend class ThreadPool;
-
-  DISALLOW_ALLOCATION();
-  DISALLOW_COPY_AND_ASSIGN(ThreadPoolData);
-};
-
-#endif  // BIN_THREAD_POOL_MACOS_H_