gallium: pipe: add get_decoder_fence vfunc
Add a get_decoder_fence vfunc that can be used to query the status
of the previous decode job denoted by 'fence' given 'timeout'.
A pointer to a fence pointer can be passed to the codecs before the
end_frame vfunc and the codec should then be responsible for allocating
a fence on command stream submission.
Signed-off-by: Daniel Almeida <daniel.almeida@collabora.com>
Reviewed-by: Leo Liu <leo.liu@amd.com>
Reviewed-by: Boyuan Zhang <Boyuan.Zhang@amd.com>
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/20133>