playing_silence was not initialized with the struct
was initialized, it was being set after the fact
which caused problems if something that relied on
playing_silence being set was called too quickly

(closes issue #18430)
Reported by: stevebrandli
Patches: 
      externalivr.patch uploaded by thedavidfactor (license 903)
Tested by: thedavidfactor, stevebrandli


git-svn-id: https://origsvn.digium.com/svn/asterisk/trunk@300121 65c4cc65-6c06-0410-ace0-fbb531ad65f3