ristretto: update to 0.8.4

0.8.4
=====
- Add missing field initializers
- Instead of thumbnails, the same icons with a crossed red circle (bug #13419)
- Resolve g_type_class_add_private() deprecation
- Glib-Critical errors to stdout: Source ID X was not found when attempting to
  remove it (bug #15268)
- Fix memory leak (bug #12034)
- Show file size in the status bar (bug #14791)
- Fix opening of PPM files (bug #14709)

* Translation updates:
  Arabic (ar), Asturian (ast), Belarusian (be), Bulgarian (bg), Catalan (ca),
  Czech (cs), Danish (da), German (de), Greek (el), English (United Kingdom)
  (en_GB), Spanish (es), Basque (eu), Finnish (fi), French (fr), Galician (gl),
  Hebrew (he), Croatian (hr), Hungarian (hu), Indonesian (id), Icelandic (is),
  Italian (it), Japanese (ja), Kazakh (kk), Korean (ko), Lithuanian (lt), Malay
  (ms), Norwegian Bokm奪l (nb), Dutch (nl), Occitan (oc), Polish (pl), Portuguese
  (pt), Portuguese (Brazil) (pt_BR), Romanian (ro), Russian (ru), Slovak (sk),
  Slovenian (sl), Albanian (sq), Serbian (sr), Swedish (sv), Telugu (te), Thai
  (th), Turkish (tr), Uighur (ug), Ukrainian (uk), Chinese (China) (zh_CN),
  Chinese (Taiwan) (zh_TW)

(gutteridge)