Instead of using the surface fence, store the fence in buffer.
This way the fence won't be overwritten when encoding multiple frames
using the same source surface and SyncBuffer will sync the correct job.
Also fixes possible crash when destroying coded buffer before calling
SyncSurface and possible leak when destroying or reusing coded buffer
with pending encode job without calling SyncSurface/SyncBuffer.
Reviewed-by: Ruijing Dong <ruijing.dong@amd.com>
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/31959>
93d434362b