linux-drm-syncobj-v1: new protocol

This is a new Linux explicit synchronization protocol based on DRM synchronization objects 1.

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• Review
• 3 ACKs
  • wlroots (@emersion)
  • GNOME (@carlosg)
  • KDE (@zzag)
  • Weston (@daniels)
• 3 implementations:
  • wlroots: wlroots/wlroots!4262 (gamescope: https://github.com/ValveSoftware/gamescope/pull/982)
  • Mesa: mesa/mesa!25709 (merged)
  • Mutter: https://gitlab.gnome.org/GNOME/mutter/-/merge_requests/3300
  • KWin: https://invent.kde.org/plasma/kwin/-/merge_requests/4693
  • xserver: xorg/xserver!967 (merged)
  • NVIDIA/egl-wayland: https://github.com/NVIDIA/egl-wayland/pull/104