em0, VLAN and bpf(?) trouble w/RELENG_5

[astesin at ukrtelecom.net]

An update:

> > I am using 5.3-STABLE FreeBSD 5.3-STABLE #1: Tue Nov  9 13:11:18 EST
> > 2004  and it works with large frames.
> 
> Ok I'm starting a make update & ... now...

So now I have RELENG_5 as of today

1. No problems with large frames. Bing -s 2000 -S 4000 -e 5000 works fine
through vlan0.

2.  trafshow -i vlan0
     ... silence ...

    Vlan0 hangs.