Merged revisions 131421 via svnmerge from

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

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r131421 | russell | 2008-07-16 15:47:53 -0500 (Wed, 16 Jul 2008) | 7 lines

Always ensure that the channel's tech_pvt reference is NULL after calling the
destroy callback.
(closes issue #13060)
Reported by: jpgrayson
Patches:
      chan_iax2_tech_pvt_crash.patch uploaded by jpgrayson (license 492)

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git-svn-id: https://origsvn.digium.com/svn/asterisk/trunk@131422 65c4cc65-6c06-0410-ace0-fbb531ad65f3