Fix for wound overlays. (#5787)

# About the pull request

Yet another disastrous consequence of that "research warcrimes" PR. For
whatever reason, it removed a line that actually was doing something
important. If we have been processing the limb (otherwise
`need_process()` should not be called at all) and after going through
all the checks decided to cease processing it (which only happens when
all damage is gone), we do need to update wounds one final time first to
remove all the overlays from wounds/bandages that have healed but have
not been removed by limb's not-every-tick update in regular `process()`.

# Explain why it's good for the game

Fixes #4764.


# Changelog

:cl:
fix: Fully healed limbs should now properly remove the overlays for
their wounds and bandages.
/:cl:

code/modules/organs/limbs.dm

@@ -580,8 +580,9 @@ This function completely restores a damaged organ to perfect condition.
 	if(brute_dam || burn_dam)
 		return TRUE
 	if(knitting_time > 0)
-		return 1
-	return 0
+		return TRUE
+	update_wounds()
+	return FALSE
 
 /obj/limb/process()