[Mesa-dev] Mesa 30 bit color depth patches, rev 4.

[Mario Kleiner]

This is mostly the same as the last series rev 3, with the following
changes:

1. Rebased onto current master, some trivial merge conflict resolved.

2. R-b's of Tapani and Marek tacked onto all patches. Only the new
   patch 22/22 is new and unreviewed.

3. Following Tapani's suggestion i moved old patch 1 to patch 6, so
   the enable for i965 30 bit formats is done after the basic dri and
   i965 bits are in place. This is more consistent with flipping the
   on-switch on gallium.

4. Added patch 22/22, so OES read type queries for glReadPixels also
   handle B10G10R10X2, not only B10G10R10A2, following Marek's advice.
   I've tested this by quickly hacking up the
   dEQP-EGL.functional.wide_color.window_1010102_colorspace_default
   test to ask for zero alpha bits, verifying via apitrace it gets
   a X2R10G10B10 format and that the precision test fails in the
   expected way, ie. with a constant alpha == 3 ( ~ 1.0f) returned
   from a fb that doesn't have an alpha channel when reading via
   glReadPixels(GL_RGBA, GL_UNSIGNED_INT_10_10_10_2_REV).

5. Finally i've dropped the nouveau patch which added a hacky
   B10G10R10X2 pixel format for visuals, which isn't actually
   supported by the driver or NVidia hardware.

   This means that depth 30 display on NVidia hardware won't work
   atm., but that needs more work on nouveau-ddx and nouveau-kms
   anyway to get it working properly.

   Prime renderoffload from a Intel or AMD display gpu to a NVidia
   gpu works, as tested on Wayland+Weston and X11, so there's some
   use to the current nouveau gallium support for depth 30.

So this one should be probably good to push after checking patch
22/22.

Thanks,
-mario