After auto init, check that the deprecated functions exist before using

After auto init, check that the deprecated functions exist before using

The functions that have been deprecated by the auto init changes are
now guarded with deprecation checks, so it's fairly easy to see if
they can be used.

In test/dtlsv1listentest, we simply remove all init and cleanup code,
as they are call automatically when needed.

Reviewed-by: Matt Caswell <matt@openssl.org>