When dnssec-policy was introduced, it implicitly set inline-signing.
But DNSSEC maintenance required either inline-signing to be enabled,
or a dynamic zone. In other words, not in all cases you want to
DNSSEC maintain your zone with inline-signing.
Change the behavior and determine whether inline-signing is
required: if the zone is dynamic, don't use inline-signing,
otherwise implicitly set it.
You can also explicitly set inline-signing to yes with dnssec-policy,
the restriction that both inline-signing and dnssec-policy cannot
be set at the same time is now lifted.
However, 'inline-signing no;' on a non-dynamic zone with a
dnssec-policy is not possible.