Merged revisions 337974 via svnmerge from

https://origsvn.digium.com/svn/asterisk/branches/10

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  r337974 | rmudgett | 2011-09-26 14:35:23 -0500 (Mon, 26 Sep 2011) | 37 lines
  
  Merged revisions 337973 via svnmerge from 
  https://origsvn.digium.com/svn/asterisk/branches/1.8
  
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    r337973 | rmudgett | 2011-09-26 14:30:39 -0500 (Mon, 26 Sep 2011) | 30 lines
    
    Fix deadlock when using dummy channels.
    
    Dummy channels created by ast_dummy_channel_alloc() should be destoyed by
    ast_channel_unref().  Using ast_channel_release() needlessly grabs the
    channel container lock and can cause a deadlock as a result.
    
    * Analyzed use of ast_dummy_channel_alloc() and made use
    ast_channel_unref() when done with the dummy channel.  (Primary reason for
    the reported deadlock.)
    
    * Made app_dial.c:dial_exec_full() not call ast_call() holding any channel
    locks.  Chan_local could not perform deadlock avoidance correctly.
    (Potential deadlock exposed by this issue.  Secondary reason for the
    reported deadlock since the held lock was part of the deadlock chain.)
    
    * Fixed some uses of ast_dummy_channel_alloc() not checking the returned
    channel pointer for failure.
    
    * Fixed some potential chan=NULL pointer usage in func_odbc.c.  Protected
    by testing the bogus_chan value.
    
    * Fixed needlessly clearing a 1024 char auto array when setting the first
    char to zero is enough in manager.c:action_getvar().
    
    (closes issue ASTERISK-18613)
    Reported by: Thomas Arimont
    Patches:
          jira_asterisk_18613_v1.8.patch (license #5621) patch uploaded by rmudgett
    Tested by: Thomas Arimont
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git-svn-id: https://origsvn.digium.com/svn/asterisk/trunk@337975 65c4cc65-6c06-0410-ace0-fbb531ad65f3