Move nfs.c:foreach_nfs_shareopt() to libshare.c:foreach_shareopt()
so that it can be (re)used in other parts of libshare.
sa_get_zfs_handle(sa_handle_t handle)
{
	sa_handle_impl_t impl_handle = (sa_handle_impl_t)handle;

	if (impl_handle == NULL)
		return (NULL);

	return (impl_handle->zfs_libhandle);
}

sa_get_zfs_handle(sa_handle_t handle)
{
	sa_handle_impl_t impl_handle = (sa_handle_impl_t)handle;

	if (impl_handle == NULL)
		return (NULL);

	return (impl_handle->zfs_libhandle);
}
