Make sure agent_tech is unregistered within unload_module(). It's in 1.2, but...

 Make sure agent_tech is unregistered within unload_module(). It's in 1.2, but was lost at some point in /trunk. #7374 (jstorm)



git-svn-id: https://origsvn.digium.com/svn/asterisk/trunk@34461 65c4cc65-6c06-0410-ace0-fbb531ad65f3