Merged revisions 165767 via svnmerge from

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

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  r165767 | tilghman | 2008-12-18 15:14:47 -0600 (Thu, 18 Dec 2008) | 8 lines
  
  Add mutexes around accesses to the IMAP library interface.  This prevents
  certain crashes, especially when shared mailboxes are used.
  (closes issue #13653)
   Reported by: howardwilkinson
   Patches: 
         asterisk-1.4.21.2-appvoicemail-sharedimap-lock.patch uploaded by howardwilkinson (license 590)
   Tested by: jpeeler
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git-svn-id: https://origsvn.digium.com/svn/asterisk/trunk@165797 65c4cc65-6c06-0410-ace0-fbb531ad65f3