backends/drm: work around amdgpu bugs with DCC modifiers
See https://gitlab.freedesktop.org/mesa/mesa/-/issues/10875 for details. The workaround
can be disabled again with the KWIN_DRM_NO_DCC_WORKAROUND=1
environment variable
See https://gitlab.freedesktop.org/mesa/mesa/-/issues/10875 for details. The workaround
can be disabled again with the KWIN_DRM_NO_DCC_WORKAROUND=1
environment variable