[NaCl SDK] nacl_mounts: wrap functions.

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"