Merged revisions 314069 via svnmerge from

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

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  r314069 | rmudgett | 2011-04-18 11:10:10 -0500 (Mon, 18 Apr 2011) | 22 lines
  
  The AsyncAGI command loop is lax in the value it returns for the return status.
  
  * Return correct status: SUCCESS/FAILED/HANGUP.  Previously, abnormal
  exits from the command loop such as hangup would return SUCCESS.
  
  * The "asyncagi break" command now returns SUCCESS and is now the only way
  to break the command loop with that status.  Previously, it returned
  FAILED.
  
  * The AMI event AsyncAGI End is no longer sent if the AsyncAGI Start event
  is not sent.  Previously, this happened because of an error setting up the
  AGI pipes.
  
  * All executed AGI commands now get an AsyncAGI Exec result event.
  Previously, if the command returned failure (because of hangup), the
  command loop just exited with FAILURE and did not send the AsyncAGI Exec
  result event.
  
  * Makes sure that the channel frame queue is empty on hangup.
  
  Review: https://reviewboard.asterisk.org/r/1183/
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git-svn-id: https://origsvn.digium.com/svn/asterisk/trunk@314080 65c4cc65-6c06-0410-ace0-fbb531ad65f3