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

native_client_sdk/src/libraries/nacl_io/kernel_wrap.h

 // 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.
 
 #ifndef LIBRARIES_NACL_IO_KERNEL_WRAP_H_
 #define LIBRARIES_NACL_IO_KERNEL_WRAP_H_
 
 #include <signal.h>
 #include <stdint.h>
 #include <stdlib.h>
@@ skipping 78 matching lines @@
 int _stat32(const char* path, struct _stat32* buf);
 int _stat64(const char* path, struct _stat64* buf);
 int _stat32i64(const char* path, struct _stat32i64* buf);
 int _stat64i32(const char* path, struct _stat64i32* buf);
 #else
 int stat(const char* path, struct stat* buf) NOTHROW;
 #endif
 int symlink(const char* oldpath, const char* newpath) NOTHROW;
 int umount(const char* path) NOTHROW;
 int NAME(unlink)(const char* path) NOTHROW;
-uint64_t usec_since_epoch();
 int utime(const char* filename, const struct utimbuf* times);
 read_ssize_t NAME(write)(int fd, const void* buf, size_t nbyte);
 
 #ifdef PROVIDES_SOCKET_API
 // Socket Functions
 int accept(int fd, struct sockaddr* addr, socklen_t* len);
 int bind(int fd, const struct sockaddr* addr, socklen_t len);
 int connect(int fd, const struct sockaddr* addr, socklen_t len);
 struct hostent* gethostbyname(const char* name);
 int getpeername(int fd, struct sockaddr* addr, socklen_t* len);
@@ skipping 11 matching lines @@
 int setsockopt(int fd, int lvl, int optname, const void* optval,
                socklen_t len);
 int shutdown(int fd, int how);
 int socket(int domain, int type, int protocol);
 int socketpair(int domain, int type, int protocl, int* sv);
 #endif  // PROVIDES_SOCKET_API
 
 EXTERN_C_END
 
 #endif  // LIBRARIES_NACL_IO_KERNEL_WRAP_H_