Fixed parts of the undead flags which were not TC'd

Ran wesnoth-optipng

Updated changelog

changelog

@@ -42,6 +42,7 @@ Version 1.5.5+svn:
      click without a close button.
  * Miscellaneous and bug fixes:
    * fixed addon update version logic (patch #1110)
+   * fixed the parts of the undead flags which were not TC'd
 
 Version 1.5.5:
  * Campaigns:
@@ -151,6 +152,7 @@ Version 1.5.4:
      with a DISABLE_EDITOR2 define to build without it.
  * Graphics:
    * New portraits: Silver Mage (male), Mage of Light (male).
+   * fixed the parts of the undead flags which were not TC'd
  * Language and i18n:
    * updated translations: Chinese (Traditional), Czech, French, Galician,
      German, Hungarian, Italian, Lithuanian, Polish