Fix reversed behavior of leavewhenempty option in queues.conf.

(closes issue #14650)
Reported by: alecdavis
Patches:
      14650.patch uploaded by mmichelson (license 60)
Tested by: mmichelson, lmadsen



git-svn-id: https://origsvn.digium.com/svn/asterisk/trunk@190250 65c4cc65-6c06-0410-ace0-fbb531ad65f3