smbd: Set SHARE_MODE_HAS_READ_LEASE when granting a read lease

smbd: Set SHARE_MODE_HAS_READ_LEASE when granting a read lease

Lazy update of the flag: Whenever we add a read lease, we have to set
the flag. Nobody except contend_level2_oplocks_begin will remove that
flag again, as this would mean a full lease traverse when removing
one. And contend_level2_oplocks_begin traverses the leases anyway

Signed-off-by: Volker Lendecke <vl@samba.org>
Reviewed-by: Ralph Boehme <slow@samba.org>