gbm_{bo,surface}_create_with_modifiers doesn't allow callers to
pass usage flags. Assume USE_SCANOUT since this is what most
callers want.

Bump the GBM ABI version so that other backends can discover when
the usage flags can be used.

Signed-off-by: Simon Ser <contact@emersion.fr>
Reviewed-by: James Jones <jajones@nvidia.com>
Reviewed-by: Daniel Stone <daniels@collabora.com>
Part-of: <!3197>