-fix for handling 408 and 481 responses to UPDATE requests in UAS before call is accepted 
-fix for allowing end() to be called from UAS_ReceivedUpdateWaitingAnswer or UAS_SentUpdateAccepted states


git-svn-id: https://svn.resiprocate.org/rep/resiprocate/main@10708 ddefafc4-47db-0310-ae44-fa13212b10f2