display: new multiplanar qualifier

Introduce a new "qualifier" on displays and display buffers, to keep track of
whether we have a single buffer for Y/U/V or if we have Y and U/V separated.

KMS display buffers are multiplanar, and X11 display buffers are
non-multiplanar since latest non-multiplanar dri2video in xf86-video-omap.

Signed-off-by: Vincent Stehlé <v-stehle@ti.com>
viddec3test: handle non-multiplanar

Latest non-multiplanar dri2video in xf86-video-omap now uses a single buffer
under x11 instead of separate Y and U/V. Adapt viddec3test, like gst-ducati
does, and keep KMS multiplanar functional.

Signed-off-by: Vincent Stehlé <v-stehle@ti.com>
display: add close "virtual" function

Change the per-display close function into a proper "virtual" function
mechanism with function pointer in the display structure. This fixes the
segfault, when closing a kms display.

Signed-off-by: Vincent Stehlé <v-stehle@ti.com>
New display kmscube

Add a new display 'kmscube', based on the kmscube application by Arvin Schnell
and Rob Clark.

This display 'kmscube' draws a rotating 3d cube with EGL on kms display, with
video mapped as a texture on the cube faces.

Signed-off-by: Vincent Stehlé <v-stehle@ti.com>
Hack! disp-kmscube: reduce u/v by 10%

Signed-off-by: Vincent Stehlé <v-stehle@ti.com>