Merged revisions 308945 via svnmerge from

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

........
  r308945 | alecdavis | 2011-02-26 07:52:53 +1300 (Sat, 26 Feb 2011) | 21 lines
  
  Fix Deadlock with attended transfer of SIP call
  
  Call path 
    sip_set_rtp_peer (locks chan then pvt)
     transmit_reinvite_with_sdp
      try_suggested_sip_codec
       pbx_builtin_getvar_helper (locks p->owner)
  
  But by the time p->owner lock was attempted, seems as though chan and p->owner were different.
  
  So in sip_set_rtp_peer, lock pvt first then lock p->owner using deadlocking methods.
  
  (closes issue #18837)
  Reported by: alecdavis
  Patches: 
        bug18837-trunk.diff3.txt uploaded by alecdavis (license 585)
  Tested by: alecdavis, Irontec, ZX81, cmaj
  
  Review: [https://reviewboard.asterisk.org/r/1126/]
........


git-svn-id: https://origsvn.digium.com/svn/asterisk/trunk@308946 65c4cc65-6c06-0410-ace0-fbb531ad65f3