minor optimizations to avoid extra calls of strlen(),
and some variable localization.
One feature worth backporting is the move of ast_variables_destroy()
to a different place in handle_uri() to avoid leaking memory
in case a uri is not found.
git-svn-id: https://origsvn.digium.com/svn/asterisk/trunk@45463 65c4cc65-6c06-0410-ace0-fbb531ad65f3