Fixes a bug in chan_iax that uses send_command to poke a peer while a channel...

Fixes a bug in chan_iax that uses send_command to poke a peer while a channel is unlocked in some cases, and because it can cause seemingly 
random failures could be related to some bugs in the tracker...


git-svn-id: https://origsvn.digium.com/svn/asterisk/trunk@118702 65c4cc65-6c06-0410-ace0-fbb531ad65f3