Fix an issue in iax2 where a call that's been rejected still kept an open...

Fix an issue in iax2 where a call that's been rejected still kept an open channel on the side that attempted to make the call (not the side of the 
call that rejected the call). Changes were load tested and also approved by Russell.


git-svn-id: https://origsvn.digium.com/svn/asterisk/trunk@132466 65c4cc65-6c06-0410-ace0-fbb531ad65f3