Fix "CNAME and other data" detection

Fix "CNAME and other data" detection

prio_type was being used in the wrong place to optimize cname_and_other.
We have to first exclude and accepted types and we also have to
determine that the record exists before we can check if we are at
a point where a later CNAME cannot appear.

(cherry picked from commit 5e49a9e4ae8d0a78fb5ac0c7b683de9a29b6b848)