Fix memory leaks

(closes issue ASTERISK-22368)
Reported by: Corey Farrell
Patches:
     issueA22368_mixmonitor_free_filename.patch uploaded by wdoekes (license 5674)


git-svn-id: http://svn.asterisk.org/svn/asterisk/branches/10@398004 f38db490-d61c-443f-a65b-d21fe96a405b