Merged revisions 275773 via svnmerge from

https://origsvn.digium.com/svn/asterisk/branches/1.4

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  r275773 | jpeeler | 2010-07-12 15:34:51 -0500 (Mon, 12 Jul 2010) | 12 lines
  
  Make user removals and traversals thread safe in meetme.
  
  Race conditions present in meetme involving the user list where a lack of
  locking has the potential for a user to be removed during a traversal or as in
  the case of the reporter after checking if the list is empty could cause a
  crash. Fixing this was done by convering the userlist to an ao2 container.
  
  (closes issue #17390)
  Reported by: Vince
  
  Review: https://reviewboard.asterisk.org/r/746/
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git-svn-id: https://origsvn.digium.com/svn/asterisk/trunk@276074 65c4cc65-6c06-0410-ace0-fbb531ad65f3