* Driver does not build for current Xorg server.

* Last upstream release was 2015, last non-trivial Git commit was 2017.

* Last Permedia card was manufactured in 1999.

* We can still use fbdev on these chips; it is unlikely that any of the
  GL 1.1 support would be useful these days, and contemporary reviews
  noted that the Rage128 and RIVA TNT performed better.

We've always depended on it, so no revbump needed; with the new Xorg
changes, we don't automatically pull it in as a silent dep.

Since GBM is busted upstream, we can't use this for Wayland or Xorg.
I'm not sure what we are meant to be using it for, but we don't need
it available everywhere in this case.

See upstream: https://gitlab.freedesktop.org/mesa/mesa/-/issues/12219

Users can override this by running 'apk add !mesa-amber', but this way
we always install drivers for the older machines when installing Mesa
drivers at all.  This way, we don't need to change Horizon etc to
support the older hardware drivers, and users can still remove it if
they know they won't ever need it.

* Additionally, use GLVND for OpenGL headers.

* Also, use RelWithDebInfo instead of RelWithDebugInfo.  This matters
  because the target CMake files installed require the build type to
  match one of the ones they define, and they define that one.

* Mesa used for the DRM backend; GLVND for EGL.

* Mesa still needed for GBM, DRM, KMS.

* Wayland enabled for both EGL and libva.

These automatically add themselves when the winsys itself is present
(libx11 or wayland), so there should be no functional change for users.

Mesa is still needed for GBM, but GLVND is needed for EGL.

* We now have Vulkan support, so add that.

* Use GLVND for GL headers.  Mesa remains for DRM.

* Mesa is used internally for GBM.

* libglvnd-dev is needed for OpenGL headers.

Includes a patch to the CMake to use libOpenGL and libGLX instead of
the legacy libGL.  We also explicitly set GLVND instead of LEGACY for
the FindOpenGL module.

* Mesa is still used for GBM and KMS.

* Only OpenGL headers are used, so replace mesa with libglvnd.

* mesa-dev is still needed for the KMS backend.

Otherwise, some xf86-video-* fail to build with missing <pciaccess.h>.

Also, declare ICU dependency explicitly so it isn't missed again.