pidl: Wireshark: Don't assign hash undef, assign it an empty array

pidl: Wireshark: Don't assign hash undef, assign it an empty array

Pick up change from Wireshark:

    commit ade6577f109e2bf741909226254b758e79a816f1
    Author: John Thacker <johnthacker@gmail.com>
    Date:   Fri Jun 21 20:27:51 2024 -0400

        pidl: Don't assign hash undef, assign it an empty array

        Perl works, but complains if warnings are on, if a hash is
        initialized to undef instead of to empty. Upstream Samba turned on
        warnings in the next commit to catch things like this.

Signed-off-by: John Thacker <johnthacker@gmail.com>
Reviewed-by: Jo Sutton <josutton@catalyst.net.nz>
Reviewed-by: Stefan Metzmacher <metze@samba.org>