Simplify buffer handling in dundi-parser.c. This also makes the code a bit

safer by removing various assumptions about sizes. (No vulnerabilities, though)

(closes issue #10977)
Reported by: dimas
Patches: 
      dundiparser.patch uploaded by dimas (license 88)


git-svn-id: https://origsvn.digium.com/svn/asterisk/trunk@85558 65c4cc65-6c06-0410-ace0-fbb531ad65f3