[NaCl SDK] nacl_io: Remove unneeded glibc syscall entry points.

native_client_sdk/src/libraries/gtest/nacl_gtest_dummy_sys.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.
-
-#if defined(__native_client__)
-#include <errno.h>
-#include <string.h>
-#include <sys/types.h>
-#endif
-
-extern "C" {
-
-#if defined(__native_client__)
-
-char* getcwd(char* buf, size_t size) __attribute__ ((weak));
-int unlink(const char* pathname) __attribute__ ((weak));
-int mkdir(const char* pathname, mode_t mode) __attribute__ ((weak));
-
-char* getcwd(char* buf, size_t size) {
-  if (size < 2) {
-    errno = ERANGE;
-    return NULL;
-  }
-
-  return strncpy(buf, ".", size);
-}
-
-int unlink(const char* pathname) {
-  errno = ENOSYS;
-  return -1;
-}
-
-int mkdir(const char* pathname, mode_t mode) {
-  errno = ENOSYS;
-  return -1;
-}
-
-#endif
-
-}  // extern "C"