tests: Test that ofp10_match bytes that should be ignored really are.

tests: Test that ofp10_match bytes that should be ignored really are.

Rob Sherwood reported a bug in OVS treatment of ofp10_match bytes that
should be ignored some time ago:

> In any case, the pktact.SingleWildcardMatch and
> pktact.AllExceptOneWildcardMatch tests were failing because it looks
> like OVS (v1.4 release) was  not matching vlan tagged packets when the
> match wildcarded vlan but the dl_vlan value (which should be ignored,
> because it is wildcarded) was non-zero.  We've worked around this in
> OFTest by making sure that the dl_vlan value is zero when vlan is
> wildcarded and now the test passes.
>
> In other words:
>
> if (ofp_match->wildcards&OFPFW_DL_VLAN) is true, then the match should
> match both tagged and untagged packets, independent of the value of
> ofp_match->dl_vlan.  OVS (seemingly) only matches tagged packets if
> ofp_match->dl_vlan == 0.

I wasn't able to spot the problem at the time, and I still don't see a
problem (perhaps it has been fixed since then), but this commit should
prevent any regression for this specific problem and for anything like it.

It would be natural to modify the parse-ofp11-match test in the same way,
but this commit doesn't do it.

Rob's original bug report is at:
https://mailman.stanford.edu/pipermail/openflow-discuss/2012-March/003107.html

Reported-by: Rob Sherwood <rob.sherwood@bigswitch.com>
Signed-off-by: Ben Pfaff <blp@nicira.com>