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.

We can enable Wayland now.  Use libglvnd for EGL and Mesa for GBM.
Ensure wraps are disabled, so it doesn't download its own gl-headers.

OpenTTD needs grfcodec to have PNG support or it will not build.

This allows us to put 'firefox-esr' back in the Standard case of Horizon,
because on PPC where firefox-esr isn't available APK will fall back to
Arctic Fox.  But on platforms where the real Firefox is available, it will
install that.

There is no reason to split EGL since all DRI drivers need the EGL
runtime now due to how glvnd works.  Similar for GL-API.

Confirmed working well on:

* Intel HD Graphics 3000/4000 (Sandy Bridge, Ivy Bridge)
* NVIDIA Fermi (GeForce GT 520, Quadro 1000M)
* AMD Radeon (r600 on ppc64, with usual known brokenness)
* LLVMpipe on Intel Iris (Raptor Lake)

in both X11 and Wayland environments.

Does not work on big endian, despite faring slightly better with my patch.
Does not seem to work on 32-bit architectures; not investigated.

See-also: https://github.com/KhronosGroup/SPIRV-LLVM-Translator/issues/2397

Reported upstream at https://github.com/KhronosGroup/glslang/issues/3799;
I'm not happy with the patch, and I feel like it can be better, but it
works and it unblocks Vulkan for beta6.

This integrates a patch that is currently sitting upstream in review.
Adding this patch corrects the tools to work on cross-endian binaries,
i.e. a big-endian system can handle little-endian shaders, and vis versa.

See-also: https://github.com/KhronosGroup/SPIRV-Tools/issues/5595

user/mesa is the latest (24.2.7), and should install everywhere.
user/mesa-be includes 24.1.7 which is needed for proper operation on
big endian platforms, hence it is only enabled for ppc/ppc64.

* Unfortunately, Intel Iris is not portable due to OpenCL issues and
  cannot be included with beta6.

* The glvnd JSON file needs to be kept with the driver.

* We can't split GL any more, so don't bother.

* The DRI driver depends on the GLX stub, which is part of mesa, so
  declare that dep explicitly.  (weak linked, so abuild can't see it)

Required for the Rust bits of Mesa's new NV Vulkan driver.

This provides graphics drivers for r100/r200 Radeons, and also
early GeForces via nouveau dri.  nv30+ are handled by Gallium.
Uses libglvnd so it can coexist with newer Mesa versions.

Needed for newer Mesa releases.

Needed for new Mesa, and provides AVC1 decoding on supported hw.

This package allows us to ship Amber and current Mesa at the same time.

Also updates the test patch to be applicable to all tests.  This patch
has been submitted upstream and the upstream URL is included.