In trunk, ast_fileexists now returns 0 for failure, instead of -1, as it did

in 1.2.  This corrected a longstanding confusion about the return value.
Unfortunately, it broke this app in the process.  (Issue 7906)


git-svn-id: https://origsvn.digium.com/svn/asterisk/trunk@42621 65c4cc65-6c06-0410-ace0-fbb531ad65f3