ldb: Release 1.2.3

ldb: Release 1.2.3

 - Intersect the index from SCOPE_ONELEVEL with the index for the search expression

    This helps ensure we do not have to scan all objects at this level
    which could be very many (one per DNS zone entry).

    However, due to the O(n*m) behaviour in the LDB index code
    we only do this for small numbers of matches on the
    filter tree.

    This behaviour will only be for ldb 1.2 and will not be kept
    long-term in LDB, versions 1.3.1 and above will instead only
    intersect when the more efficient GUID index is in use.

    Finally, disallowDNFilter now applies to SCOPE_ONELEVEL banning
    dn= as a filter string when so configured.

BUG: https://bugzilla.samba.org/show_bug.cgi?id=13191

Signed-off-by: Andrew Bartlett <abartlet@samba.org>
Reviewed-by: Garming Sam <garming@catalyst.net.nz>