Remove unused files linux.cc/.h and linuxfdwalk.c/.h.

webrtc/base/linuxfdwalk.h

-/*
- *  Copyright 2004 The WebRTC Project Authors. All rights reserved.
- *
- *  Use of this source code is governed by a BSD-style license
- *  that can be found in the LICENSE file in the root of the source
- *  tree. An additional intellectual property rights grant can be found
- *  in the file PATENTS.  All contributing project authors may
- *  be found in the AUTHORS file in the root of the source tree.
- */
-
-#ifndef WEBRTC_BASE_LINUXFDWALK_H_
-#define WEBRTC_BASE_LINUXFDWALK_H_
-
-#ifdef __cplusplus
-extern "C" {
-#endif
-
-// Linux port of SunOS's fdwalk(3) call. It loops over all open file descriptors
-// and calls func on each one. Additionally, it is safe to use from the child
-// of a fork that hasn't exec'ed yet, so you can use it to close all open file
-// descriptors prior to exec'ing a daemon.
-// The return value is 0 if successful, or else -1 and errno is set. The
-// possible errors include any error that can be returned by opendir(),
-// readdir(), or closedir(), plus EBADF if there are problems parsing the
-// contents of /proc/self/fd.
-// The file descriptors that are enumerated will not include the file descriptor
-// used for the enumeration itself.
-int fdwalk(void (*func)(void *, int), void *opaque);
-
-#ifdef __cplusplus
-}  // extern "C"
-#endif
-
-#endif  // WEBRTC_BASE_LINUXFDWALK_H_