(closes issue #13493)

(closes issue #13493)
Reported by: mdu113
Patches:
      bug13493.diff uploaded by jpeeler (license 325)
Tested by: mdu113

Changed park_call_full to hold the parkinglot lock a little longer, which protects the parkeduser struct from being freed out from underneath. Made sure that the parking extension is added to the parking context while holding the lock thereby ensuring that there are no spurious warnings from removal attempts when a hangup occurs while the parking lot is being announced.

git-svn-id: https://origsvn.digium.com/svn/asterisk/branches/1.4@143270 65c4cc65-6c06-0410-ace0-fbb531ad65f3