Avoid crashing when installing a duplicate translation path with a lower cost.

(closes issue #17092)
Reported by: moy
Patches:
      translate.rev254273.patch uploaded by moy (license 222)
Tested by: moy


git-svn-id: https://origsvn.digium.com/svn/asterisk/trunk@277143 65c4cc65-6c06-0410-ace0-fbb531ad65f3