tend ltend: Fix to skip dead ships and land units for deities

tend ltend: Fix to skip dead ships and land units for deities

Tending to a dead ship destroys, and tending from a dead ship revives.
Has always been that way.  Not actually a problem for ltend anymore,
because the dead can't carry or be carried since commit 64a53c90f0,
v4.3.17.

Fix by checking !own in addition to !player->owner

Signed-off-by: Markus Armbruster <armbru@pond.sub.org>