This update fixes the problem reported in bug 8551; that ast_app_getdata()...

This update fixes the problem reported in bug 8551; that ast_app_getdata() behaves differently in trunk for the case of a null prompt.

git-svn-id: https://origsvn.digium.com/svn/asterisk/trunk@48388 65c4cc65-6c06-0410-ace0-fbb531ad65f3