ebtables: Include 'bitmask' value when comparing rules

ebtables: Include 'bitmask' value when comparing rules

The former FIXME comment pointed at the fact that struct ebt_entry does
not have a 'flags' field (unlike struct ipt_ip). In fact, ebt_entry's
equivalent is 'bitmask' field. Comparing that instead is the right
thing to do, even though it does not seem to make a difference in
practice: No rule options alter just the bitmask value, nor is it
possible to fill an associated field with default values (e.g. all-zero
MAC and mask).

Since the situation described above might change and there is a slight
performance improvement in some cases (e.g. comparing rules differing
only by specified/omitted source/dest MAC address), add the check
anyway.

Suggested-by: Michael Estner <michaelestner@web.de>
Signed-off-by: Phil Sutter <phil@nwl.cc>