Proposal: Mesa 25.3.3 backport for trixie-backports

Hi debian-backports team,

I've been working on a backport of Mesa 25.3.3 for trixie-backports. I=
=E2=80=99m looking for some feedback or a sponsor to help get this uploaded=
.

I noticed that the discussion in bug #1132617 has been leaning towards the =
26.0.x series, but I thought 25.3.3 might be a safer, lower-risk intermedia=
te step. It includes the important CVE-2026-40393 fixes and brings in some =
much-needed improvements for newer hardware.

I've kept the changes as minimal as possible, mainly sticking to `debian/` =
modifications:

-   Adjusted LLVM (21 =E2=86=92 19) and `spirv-tools` to match Trixie's sta=
ck.
-   Relaxed some dependencies (libdrm-dev, DirectX-Headers).
-   Disabled the native D3D12 driver since it's not used on Linux.
-   Included a few necessary patches (meson scope fix and the CVE fixes).

I've already tested this on real hardware (Intel Arc B580) and it's running=
 stably with Vulkan 1.4.309 and OpenGL 4.6.

You can find the debdiff here (https://stornic56hub.duckdns.org/git/stornic=
56/mesa-debian/raw/branch/main/debdiffs/mesa-v25.3.3/mesa_25.3.3-1~bpo13+1.=
debdiff). Since it's about 10MB (due to the new source files for the CVE pa=
tches), I've also hosted it in my repository (https://stornic56hub.duckdns.=
org/git/stornic56/mesa-debian/releases/tag/v25.3.3) for easier access.

I'm happy to help with the maintenance or updates as new releases come out.=
 Let me know if this approach makes sense to you or if you'd like me to adj=
ust anything.

Thanks for all the work you do on backports!

Best regards,

stornic56