Add one flag enum value in linux-dmabuf-unstable-v1.xml to indicate secure buffer

Hi,

I see https://gitlab.freedesktop.org/wayland/wayland-protocols/-/blob/main/unstable/linux-dmabuf/linux-dmabuf-unstable-v1.xml#L239 has flag "interlaced" to inicate content is interlaced, I wonder if open source could add one flag "secured" to indicate the content is protected.

The use case is secure video playback:

• client. gbm_bo_create with usage GBM_BO_USE_PROTECTED
• weston. gl-renderer to create protected context for this flag, egl extension EGL_PROTECTED_CONTENT_EXT or go through direct display path.

Could the open source consider add this flag in the protocol? or Is there any other way to do this? Thank you!

Best Regards Nancy