kmscube: simple example using kms+gbm

[Rob Clark]

>From time to time I've been getting questions about how to use gl/egl
without x11.  And I would point them at Jesse's blog post:

  http://virtuousgeek.org/blog/index.php/jbarnes/2011/10/31/writing_stanalone_programs_with_egl_and_

But I wanted some simple example that was updated to work w/ the gbm
surface stuff, instead of the surfaceless_gles2 extension, but a bit
simpler than kmscon or weston.  So I whipped up a simple rotating cube
test:

  https://github.com/robclark/kmscube
  git://github.com/robclark/kmscube.git

Hopefully somebody finds this useful.  I've tested this on i915 and on
panda (with the hopefully-soon-to-be-released pvr gbm/kms support).

BR,
-R