This type is useful beyond the scope of winsys.
It can now be used without being lumbered with a dependency on
pvr_winsys.h. Since pvr_winsys.h is used by pvr_private.h, this can be
a common cause for circular dependencies during development.
Signed-off-by: Matt Coster <matt.coster@imgtec.com>
Reviewed-by: Karmjit Mahil <Karmjit.Mahil@imgtec.com>
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/17488>