Merged revisions 279946 via svnmerge from

Merged revisions 279946 via svnmerge from
https://origsvn.digium.com/svn/asterisk/branches/1.6.2

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  r279946 | dvossel | 2010-07-27 15:54:32 -0500 (Tue, 27 Jul 2010) | 24 lines

  Merged revisions 279945 via svnmerge from
  https://origsvn.digium.com/svn/asterisk/branches/1.4

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    r279945 | dvossel | 2010-07-27 15:33:40 -0500 (Tue, 27 Jul 2010) | 19 lines

    remove empty audiohook write list on channel

    If a channel has an audiohook write list created on it, that
    list stays on the channel until the channel is destroyed.  There
    is no reason to keep that list on the channel if it becomes empty.
    If it is empty that just means we are doing needless translating
    for every ast_read and ast_write.  This patch removes the audiohook
    list from the channel once it is detected to be empty on either a
    read or write.  If a audiohook is added back to the channel after
    this list is destroyed, the list just gets recreated as if it never
    existed to begin with.

    (closes issue #17630)
    Reported by: manvirr

    Review: https://reviewboard.asterisk.org/r/799/
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git-svn-id: https://origsvn.digium.com/svn/asterisk/branches/1.8@279949 65c4cc65-6c06-0410-ace0-fbb531ad65f3