The SIP TCP/TLS worker threads were created joinable but noone could join
them if they died on their own.
* Fix the SIP TCP/TLS worker threads to not be created joinable.
* _sip_tcp_helper_thread() only needs one parameter since the pvt
parameter is only passed in as NULL and never used.
(closes issue ASTERISK-19203)
Reported by: Steve Davies
Review: https://reviewboard.asterisk.org/r/1714/
git-svn-id: https://origsvn.digium.com/svn/asterisk/branches/1.8@356677 65c4cc65-6c06-0410-ace0-fbb531ad65f3