modesetting vs intel in 10.0

[nia <nia%NetBSD.org@localhost>]

After some testing on a Skylake machine, I've concluded
that xf86-video-modesetting is far superior to xf86-video-intel
on that generation of Intel hardware - the most obvious thing
is that modesetting has functional VSync and superior 3D performance
with less tearing.

Only problem is that we default to intel, modesetting you need
to choose explicitly through xorg.conf.

I also found similar problems in "radeon", but found that
modesetting would somehow pick a display mode that the monitor
didn't support. Maybe this is actually a drmkms bug - I'm not
sure.

But maybe modesetting is mature enough (and intel bad enough)
to warrant being the default for Intel GPUs.