s3:smbd: only clear LEASE_READ if there's no read lease is left

s3:smbd: only clear LEASE_READ if there's no read lease is left

If contend_level2_oplocks_begin_default() skips break it's
own lease, we should not clear SHARE_MODE_LEASE_READ
in share_mode_data->flags.

Otherwise that lease won't see any lease break notifications
for writes from other clients (file handles not using the same lease
key).

So we need to count the number existing read leases (including
the one with the same lease key) in order to know it's
safe to clear SMB2_LEASE_READ/SHARE_MODE_LEASE_READ.

Otherwise the next run (likely from another client)
will get the wrong result from file_has_read_lease().

BUG: https://bugzilla.samba.org/show_bug.cgi?id=15148

Signed-off-by: Stefan Metzmacher <metze@samba.org>
Reviewed-by: Ralph Boehme <slow@samba.org>
Autobuild-User(master): Jeremy Allison <jra@samba.org>
Autobuild-Date(master): Thu Aug 18 19:41:33 UTC 2022 on sn-devel-184