Fix a bug where a timer would be created but not acknowledged.

This scenario crept up if chan_iax2 was loaded with no configuration file present.
It would create a timer and tell it to go at an interval but the thread that normally
acknowledges it would not be created because no configuration file was present. The timer
will now be closed if no configuration file is present.

(closes issue #15014)
Reported by: madkins


git-svn-id: https://origsvn.digium.com/svn/asterisk/trunk@192808 65c4cc65-6c06-0410-ace0-fbb531ad65f3