ERF: Make ERF wiretap forwards compatible.

ERF: Make ERF wiretap forwards compatible.

Dissector has always been able to cope with unknown record types so pass them
through (and call the data dissector from the ERF dissector in this case).
Previously was stopping processing on the first unrecognized record which is
very unhelpful for otherwise valid files that have new types mixed in.

Remove ERF type check altogether from open heuristic as ERF type could be past
48 in future and with more extension headers bit any byte value could be valid.
Also allow setting ERF_RECORDS_TO_CHECK to 0 to force skipping the heuristic.

Change-Id: I8331eef30ba2e949564f418b3100bd73b8f58116
Reviewed-on: https://code.wireshark.org/review/15361
Reviewed-by: Michael Mann <mmann78@netscape.net>
Petri-Dish: Michael Mann <mmann78@netscape.net>
Tested-by: Petri Dish Buildbot <buildbot-no-reply@wireshark.org>
Reviewed-by: Anders Broman <a.broman58@gmail.com>