Fix more errors revealed by enum-to-integer conversion warnings.

Change-Id: Ib28af874cbac0623ed94e7558f3711e9a1b03a2d
Reviewed-on: https://code.wireshark.org/review/2874
Reviewed-by: Guy Harris <guy@alum.mit.edu>
(cherry picked from commit 8481c438614427a9249aa20e31062e3bf7a86a89)
Reviewed-on: https://code.wireshark.org/review/2875