astobj2: Unregister debug CLI commands at exit

(issue ASTERISK-22467)
Reported by: Corey Farrell
Patches:
    astobj2-clean-debug-cli-1.8-11.patch uploaded by coreyfarrell (license 5909)
    astobj2-clean-debug-cli-12up.patch uploaded by coreyfarrell (license 5909)
........

Merged revisions 401781 from http://svn.asterisk.org/svn/asterisk/branches/1.8


git-svn-id: https://origsvn.digium.com/svn/asterisk/branches/11@401783 65c4cc65-6c06-0410-ace0-fbb531ad65f3