s3: VFS: fruit. Implement fsync_send()/fsync_recv().

s3: VFS: fruit. Implement fsync_send()/fsync_recv().

For type == ADOUBLE_META, fio->fake_fd is true so
writes are already synchronous, just call tevent_req_post().

For type == ADOUBLE_RSRC we know we are configured
with FRUIT_RSRC_ADFILE (because fruit_must_handle_aio_stream()
returned true), so we can just call SMB_VFS_NEXT_FSYNC_SEND()
after replacing fsp with fio->ad_fsp.

Remove knownfail.

BUG: https://bugzilla.samba.org/show_bug.cgi?id=15182

Signed-off-by: Jeremy Allison <jra@samba.org>
Reviewed-by: Ralph Böhme <slow@samba.org>