Send proper SIP error message improperly when we can't allocate dialog (out of...

Send proper SIP error message improperly when we can't allocate dialog (out of file handles is one cause)


git-svn-id: https://origsvn.digium.com/svn/asterisk/trunk@47660 65c4cc65-6c06-0410-ace0-fbb531ad65f3