When sculpting and doing a image render the workbench used the sculpt
batch what is created by a different GPU context and would not show up.
In debug builds an assert for this case is checked. I rechecked all
`use_sculpt_pbvh` that it also checked if it was rendering. Only the
workbench deferred didn't do this for the default render mode.
With this change the user can render a workbench render directly from
sculpt mode.
9954cbfca6