virgl: push uint64_t fence_id down into each context submit_fence

makes uint64_t fence_id the standard for the virglrenderer abstraction,
forcing each context to decide what to do with it on their own. For now
all contexts immediately cast it back to (void*) and treat as a
fence_cookie (the old behavior). On 32-bit systems, this already had the
undesirable effect of truncating the 64-bit fence id passed by the
virtio-gpu device so nothing changes.

Part-of: <https://gitlab.freedesktop.org/virgl/virglrenderer/-/merge_requests/806>
6 files changed