First stab at mv643xx; port almost complete (mii stuff missing)
and compiles -- no tests yet!

was delayed by waf not printing compiler warnings by default!

Three little typos cost me almost a day:
  - missing 'return 0;' at the end of mve_attach()
  - two bad pointers (wrong type) used
All of these would have been found within minutes had the
warnings not been disabled :-(

The recursive lock takes care of this...

Testing (TCP with larger amounts of data while MVETH_TESTING
was defined which reduces the ring sizes to very small numbers)
revealed that the BSD stack honours the 'sendqlen' and
never hands us chains exceeding the ring size.

…r statistics

The 'legal' access by means of a special ioctl() is way too cumbersome
when you need to do quick diagnosis.

avoid using struct members directly.