Delete shared/platform/osx/strnlen_osx.c.

src/shared/platform/osx/strnlen_osx.c

-/*
- * Copyright 2008 The Native Client 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 <sys/stat.h>
-#include <sys/types.h>
-
-#include <fcntl.h>
-#include <string.h>
-#include <unistd.h>
-
-size_t strnlen(const char* string, size_t max);
-
-size_t strnlen(const char* string, size_t max) {
-  const char* end = (const char*)memchr(string, '\0', max);
-  return end ? (size_t)(end - string) : max;
-}