[NaCl SDK] nacl_io: use standard __BEGIN/__END_DECLS in poll.h

native_client_sdk/src/libraries/nacl_io/include/sys/poll.h

 /* Copyright (c) 2013 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. */
 
 #ifndef LIBRARIES_NACL_IO_INCLUDE_SYS_POLL_H_
 #define LIBRARIES_NACL_IO_INCLUDE_SYS_POLL_H_
 
 #include <stdint.h>
-
-#include "sdk_util/macros.h"
-
-EXTERN_C_BEGIN
+#include <sys/cdefs.h>
 
 /* This header adds definitions of flags and structures for use with poll on
  * toolchains with 'C' libraries which do not normally supply poll. */
 
 /* Node state flags */
 #define POLLIN   0x0001   /* Will not block READ select/poll. */
 #define POLLPRI  0x0002   /* There is urgent data to read. */
 #define POLLOUT  0x0004   /* Will not block WRITE select/poll. */
 #define POLLERR  0x0008   /* Will not block EXECPT select/poll. */
 #define POLLHUP  0x0010   /* Connection closed on far side. */
 #define POLLNVAL 0x0020   /* Invalid FD. */
 
 /* Number of file descriptors. */
 typedef int nfds_t;
 
 struct pollfd {
   int fd;
   uint16_t events;
   uint16_t revents;
 };
 
+__BEGIN_DECLS
+
 int poll(struct pollfd* __fds, nfds_t __nfds, int __timeout);
 
-EXTERN_C_END
+__END_DECLS
 
 #endif  /* LIBRARIES_NACL_IO_INCLUDE_SYS_POLL_H_ */