Merged revisions 320796 via svnmerge from

https://origsvn.digium.com/svn/asterisk/branches/1.8

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  r320796 | rmudgett | 2011-05-25 11:23:11 -0500 (Wed, 25 May 2011) | 17 lines
  
  Give zombies a safe channel driver to use.
  
  Recent crashes from zombie channels suggests that they need a safe home to
  goto.  When a masquerade happens, the physical part of the zombie channel
  is hungup.  The hangup normally sets the channel private pointer to NULL.
  If someone then blindly does a callback to the channel driver, a crash is
  likely because the private pointer is NULL.
  
  The masquerade now sets the channel technology of zombie channels to the
  kill channel driver.
  
  Related to the following issues:
  (issue #19116)
  (issue #19310)
  
  Review: https://reviewboard.asterisk.org/r/1224/
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git-svn-id: https://origsvn.digium.com/svn/asterisk/trunk@320820 65c4cc65-6c06-0410-ace0-fbb531ad65f3