synchronize different asn1c APER forks
Contrary to when we started, Openairinterface meanwhile has their code at least in a git repository, see https://gitlab.eurecom.fr/oai/asn1c
However, their fork is based on a 2013 version of asn1c. Ours is a rebase to 201504.
Let's re-sync with what OAI has developed, validate that against a to-be-created testsuite (#2436) and eventually aim for mainline inclusion.
It's sad that Eurecom or now OAI with their much larger team + budget is not doing that but leaving it to third parties.