[NaCl SDK] Remove syscalls wrappers for chmod and unlink.

native_client_sdk/src/libraries/nacl_io/kernel_wrap_dummy.cc

 // 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.
 
 // The Chromium build system defines __linux__ even for native client builds,
 // so guard against __native_client__ being defined as well.
 #if defined(WIN32) || (defined(__linux__) && !defined(__native_client__))
 
 #include <errno.h>
 
@@ skipping 60 matching lines @@
     return -1;
 
   *nwrote = rtn;
   return 0;
 }
 
 void _real_exit(int status) {
   exit(status);
 }
 
+int _real_getcwd(char* pathname, size_t len) {
+  return ENOSYS;
+}
+
 #endif
 
 // The Chromium build system defines __linux__ even for native client builds,
 // so guard against __native_client__ being defined as well.
 #if defined(__linux__) && !defined(__native_client__)
 
 void kernel_wrap_init() {
 }
 
 void kernel_wrap_uninit() {
 }
 
 #endif