b513389400
`dzn_instance_create` will call `dzn_instance_destroy` when the d3d12 library fails to load. Just like the issue in `d3d12_screen`, this will lead to a crash because `d3d12_mod` is NULL. To fix this, only close the library after if it was actually opened. Cc: mesa-stable Reviewed-by: Jesse Natalie <jenatali@microsoft.com> Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/20145>