objectclass_attrs: Only abort on a missing attribute when an attribute is both MUST...

objectclass_attrs: Only abort on a missing attribute when an attribute is both MUST and replicated

If an attribute is not replicated or constructed, it is quite normal for
it to be missing. This is the case with both rIDNextRid and
rIDPreviousAllocationPool. This currently prevents us switching the RID
master. On Windows, missing this attribute does not cause any problems
for the RID manager.

We may now remove the knownfail entry added earlier.

Signed-off-by: Clive Ferreira <cliveferreira@catalyst.net.nz>
Reviewed-by: Andrew Bartlett <abartlet@samba.org>
Pair-programmed-with: Garming Sam <garming@catalyst.net.nz>
Pair-programmed-with: Bob Campbell <bobcampbell@catalyst.net.nz>

BUG: https://bugzilla.samba.org/show_bug.cgi?id=12394

Autobuild-User(master): Garming Sam <garming@samba.org>
Autobuild-Date(master): Wed Nov  2 01:28:44 CET 2016 on sn-devel-144