This one is a bit of a tough nut to deal with gracefully. Zink has a set
of base-requirements that we always require. There's no Gallium caps to
report these missing features, so we're essentially left with two options:

1. Fail to create the screen.
2. Ignore the missing fetures.

Solution 1 will lead to difficulties bringing up a new Vulkan driver on
Zink, and solution 2 will lead to mis-rendering.

Since Zink is mostly an opt-in driver to use when there's no OpenGL driver
available, we should probably do 2 for now. It seems better to have some
mis-rendering than no rendering at all.

But let's at least check, and print a warning. That way people get to
know what's up.

Reviewed-By: Mike Blumenkrantz <michael.blumenkrantz@gmail.com>
Part-of: <mesa/mesa!9925>