Really fix the ltree_search_dname issue.

Basically, b327c75e screwed this up several months ago, and
  recent commits 1c49e3bd and ee2d4b72 were short-sighted
  attempts to correct it before I realized the whole original
  commit was in error.  Related commit 9af5fb35 in dnspacket.c
  was examined as well, and actually is valid and should remain.