[ofw] [RFC] winverbs implementation approach

[Sean Hefty]

>I will see about avoiding the allocations.

I ran some tests on the Linux stack creating/destroying rdma_cm_id's.  This
involves an IOCTL to the kernel, but does not allocate HW resources.  The
performance difference between allocating memory versus using a stack variable
was less than 0.5%.  (It was easiest for me to run tests on Linux, so my hope is
that Windows performance would be similar.)  If HW resources were allocated, the
difference would be smaller.

Given this, I don't think it's worth the code complexity to try to optimize out
the memory allocation.  As an alternative, I would like to consider moving the
IOCTL calls into the uvp itself at some unspecified future point in time, which
I hope will provide additional optimizations as well.

- Sean