Set stream flags to zero upon initialization.

When the XMPP over TLS/SSL connection resets for some reason, it is
wrongly believed as being secured, which makes the re-connection
process endlessly fail. This was reported by mvanbaak in issue #11644.

git-svn-id: https://origsvn.digium.com/svn/asterisk/trunk@95794 65c4cc65-6c06-0410-ace0-fbb531ad65f3