Cleanup event on exit.

Cleanup event on exit.

* Cleanup CLI commands on exit.

* v10 only: Merged v1.8 -r374177 change to event.c missed in v10 -r374178.

(issue ASTERISK-20649)
Reported by: Corey Farrell
Patches:
      event_shutdown-10-only.patch (license #5909) patch uploaded by Corey Farrell
      event_shutdown-1_8-11-trunk.patch (license #5909) patch uploaded by Corey Farrell
........

Merged revisions 377708 from http://svn.asterisk.org/svn/asterisk/branches/1.8

git-svn-id: https://origsvn.digium.com/svn/asterisk/branches/10@377709 65c4cc65-6c06-0410-ace0-fbb531ad65f3