Log Message:
Update xlockmore to 5.18. Changes:

  toneclock coredump fix for 5.17 version thanks to Jouk Jansen.
  Invalid mode added.  :)  lock the screen if an invalid mode is specified
    "xlock -mode tom" like "xlock -modelist bug,tom"
  errno fix in passwd.c for DragonFly thanks to Joerg Sonnenberger
    <joerg AT britannica.bec.de>.
  PAM fixes for when 1. TTY is not set to DISPLAY xlock can fail, 2. Tidy
    fixes for PAM_BAIL.  Thanks to George D M Ross <gdmr AT inf.ed.ac.uk>.
  Notes from Marcelo Vianna <mfvianna AT centroin.com.br> on morph3d added
    as comments to morph3d.c.