Remove unused functions from src/libudev/util.c

We remove the following unused functions:

  ascii_strlower
  block_get_whole_disk
  bus_path_escape
  can_sleep
  can_sleep_disk
  cescape
  chars_intersect
  chvt
  close_many
  close_pipe
  columns_lines_cache_reset
  copy_file
  cpu_set_malloc
  decchar
  default_signals
  default_term_for_tty
  delete_chars
  dir_is_empty
  draw_special_char
  dual_timestamp_deserialize
  dual_timestamp_serialize
  execute_directory
  fchmod_and_fchown
  fd_cloexec
  fd_inc_rcvbuf
  fd_nonblock
  filename_is_safe
  first_word
  fork_agent
  format_bytes
  format_timestamp_pretty
  fstab_node_to_udev_node
  fstype_is_network
  getenv_for_pid
  get_files_in_directory
  get_home_dir
  gethostname_malloc
  getlogname_malloc
  get_parent_of_pid
  get_process_cmdline
  get_process_exe
  get_process_gid
  get_process_uid
  get_starttime_of_pid
  getttyname_harder
  get_user_creds
  getusername_malloc
  glob_exists
  hostname_cleanup
  hostname_is_set
  hostname_is_valid
  ignore_signals
  in_charset
  in_group
  in_search_path
  is_device_path
  is_kernel_thread
  is_valid_documentation_url
  kexec_loaded
  kill_and_sigcont
  load_env_file
  make_console_stdio
  make_null_stdio
  parse_bytes
  parse_nsec
  parse_pid
  parse_timestamp
  pipe_eof
  plymouth_running
  prot_from_flags
  readlink_and_canonicalize
  release_terminal
  rename_process
  replace_env_argv
  reset_all_signal_handlers
  rmdir_parents
  rm_rf_dangerous
  running_in_chroot
  setrlimit_closest
  sigaction_many
  signal_from_string_try_harder
  sigset_add_many
  socket_from_display
  startswith_no_case
  status_welcome
  strdup_or_null
  string_is_safe
  strreplace
  symlink_atomic
  tty_is_console
  undecchar
  vt_disallocate
  wait_for_terminate_and_warn
  warn_melody
  write_env_file
  write_one_line_file_atomic
  xopendirat

Signed-off-by: Anthony G. Basile <blueness@gentoo.org>