[PATCH libdrm] tests: skip drmdevice test if the machine doesn't have any drm device

[Daniel Stone]

On Fri, 9 Nov 2018 at 19:13, Eric Engestrom <eric.engestrom at intel.com> wrote:
> Error message was invalid too, negative values aren't the number of
> devices, they're errno error codes.
>
> Signed-off-by: Eric Engestrom <eric.engestrom at intel.com>

Reviewed-by: Daniel Stone <daniels at collabora.com>