addr_resolution_dlg.c: "OK" button should *do* something: treat as cxl.

   Also: remove vestigial line of commented-out code.

Change-Id: Ieb41a0e39a4e0ec14031b1dbd38fc0d7ad47a635
Reviewed-on: https://code.wireshark.org/review/3278
Reviewed-by: Bill Meier <wmeier@newsguy.com>