Merged revisions 324048 via svnmerge from

Merged revisions 324048 via svnmerge from
https://origsvn.digium.com/svn/asterisk/branches/1.8

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  r324048 | twilson | 2011-06-16 17:35:41 -0500 (Thu, 16 Jun 2011) | 8 lines

  Lock the channel before calling the setoption callback

  The channel needs to be locked before calling these callback functions. Also,
  sip_setoption needs to lock the pvt and a check p->rtp is non-null before using
  it.

  Review: https://reviewboard.asterisk.org/r/1220/
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git-svn-id: https://origsvn.digium.com/svn/asterisk/trunk@324050 65c4cc65-6c06-0410-ace0-fbb531ad65f3