"device:" entry.
* fhandler.h (fhandler_socket::open): New method.
(fhandler_pipe::open): New method.
* fhandler_proc.cc (fhandler_proc::exists): Return -2 in case of
/proc/self.
* fhandler_process.cc (fhandler_process::exists): Return -2 in
case of symlinks, -3 for pipes and -4 for sockets.
(fhandler_process::fstat): Handle pipes and sockets.
(fhandler_process::open): Handle opening /proc/<pid>/fd.
(fhandler_process::fill_filebuf): Generate empty names for
non exisiting file descriptors.
* fhandler_socket.cc (fhandler_socket::get_proc_fd_name): Always
generate "socket:[number]" strings as on Linux.
(fhandler_socket::open): New method.
(fhandler_socket::fstat): Always return socket type.
* path.cc (symlink_info::set): Remove unused second parameter.
(path_conv::check): Handle pipes and sockets in /proc.
Set correct device type for AF_LOCAL sockets.
* pinfo.cc (_pinfo::commune_recv): Generate empty names for
non exisiting file descriptors.
(_pinfo::fd): Ditto.
* pipe.cc (fhandler_pipe::open): New method.