Add a note to document how the temporary 'pvt' should be initialized

before using it.
I am unclear on the details right now so i hope someone can comment
more. The obvious (and lazy) approach would be to bzero() all of it
(except for the string pool), but isn't that too much work ?
Feedback wanted here...



git-svn-id: https://origsvn.digium.com/svn/asterisk/trunk@76313 65c4cc65-6c06-0410-ace0-fbb531ad65f3