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

runtime/bin/eventhandler_macos.h

 // 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_EVENTHANDLER_MACOS_H_
 #define BIN_EVENTHANDLER_MACOS_H_
 
 #if !defined(BIN_EVENTHANDLER_H_)
 #error Do not include eventhandler_macos.h directly; use eventhandler.h instead.
 #endif
@@ skipping 78 matching lines @@
   SocketData* GetSocketData(intptr_t fd);
   void SendData(intptr_t id, Dart_Port dart_port, intptr_t data);
   void StartEventHandler();
 
  private:
   intptr_t GetTimeout();
   bool GetInterruptMessage(InterruptMessage* msg);
   struct pollfd* GetPollFds(intptr_t* size);
   void HandleEvents(struct pollfd* pollfds, int pollfds_size, int result_size);
   void HandleTimeout();
-  static void* Poll(void* args);
+  static void Poll(uword args);
   void WakeupHandler(intptr_t id, Dart_Port dart_port, int64_t data);
   void HandleInterruptFd();
   void SetPort(intptr_t fd, Dart_Port dart_port, intptr_t mask);
   intptr_t GetPollEvents(struct pollfd* pollfd);
 
   SocketData* socket_map_;
   intptr_t socket_map_size_;
   int64_t timeout_;  // Time for next timeout.
   Dart_Port timeout_port_;
   int interrupt_fds_[2];
 };
 
 
 #endif  // BIN_EVENTHANDLER_MACOS_H_