[NaCl SDK] Enable linux host build for nacl_io and nacl_io_tests.

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.
+
+#if defined(WIN32) || defined(__linux__)
+
+#include <errno.h>
+
+#include "nacl_io/kernel_wrap.h"
+#include "nacl_io/kernel_wrap_real.h"
+
+// "real" functions, i.e. the unwrapped original functions. For Windows/Linux
+// host builds we don't wrap, so the real functions aren't accessible. In most
+// cases, we just fail.
+
+int _real_close(int fd) {
+  return ENOSYS;
+}
+
+int _real_fstat(int fd, struct stat *buf) {
+  return 0;
+}
+
+int _real_getdents(int fd, void* nacl_buf, size_t nacl_count, size_t *nread) {
+  return ENOSYS;
+}
+
+int _real_lseek(int fd, off_t offset, int whence, off_t* new_offset) {
+  return ENOSYS;
+}
+
+int _real_mkdir(const char* pathname, mode_t mode) {
+  return ENOSYS;
+}
+
+int _real_mmap(void** addr, size_t length, int prot, int flags, int fd,
+               off_t offset) {
+  return ENOSYS;
+}
+
+int _real_munmap(void* addr, size_t length) {
+  return ENOSYS;
+}
+
+int _real_open(const char* pathname, int oflag, mode_t cmode, int* newfd) {
+  return ENOSYS;
+}
+
+int _real_open_resource(const char* file, int* fd) {
+  return ENOSYS;
+}
+
+int _real_read(int fd, void *buf, size_t count, size_t *nread) {
+  *nread = count;
+  return 0;
+}
+
+int _real_rmdir(const char* pathname) {
+  return ENOSYS;
+}
+
+int _real_write(int fd, const void *buf, size_t count, size_t *nwrote) {
+  int rtn = write(fd, buf, count);
+  if (rtn < 0)
+    return -1;
+
+  *nwrote = rtn;
+  return 0;
+}
+
+#endif
+
+#if defined(__linux__)
+
+void kernel_wrap_init() {
+}
+
+void kernel_wrap_uninit() {
+}
+
+#endif