Import revision 4196 from pjproject trunk. Fix a crash issue when starting ICE...

Import revision 4196 from pjproject trunk. Fix a crash issue when starting ICE connectivity checks and immediately destroying the ICE session. This was exposed by the SIP CCSS test.

Full fix for this issue will be worked on as a medium to long term roadmap item.

pjroject issue viewable at https://trac.pjsip.org/repos/ticket/1548


git-svn-id: https://origsvn.digium.com/svn/asterisk/trunk@369703 65c4cc65-6c06-0410-ace0-fbb531ad65f3