Count AVPs in #diameter_avp.index

The index field in record diameter_avp was previously used to enumerate
AVPs so that the list could be returned in some cases, since
diameter_codec:collect_avps/2 (now /1) reversed the order. That's no
longer the case as of the grandparent commit, so use the field to
enumerate instances of the same AVP instead, and only when arities are
being checked, to save having to look them up in the map when checking
for 5009 errors, or counting AVPs at all in diameter_codec:collect_avps/1.

0 files changed, 0 insertions, 0 deletions