r16972: Replace the sequence_number function pointer in ldb with the ldb flags.

r16972: Replace the sequence_number function pointer in ldb with the ldb flags.

The function pointer was meant to be unused, this patch fixes
partition.c to use ldb_sequence_number().  (No backend provided the
pointer any more).

Set the flags onto the ldb structure, so that all backends opened by
the partitions module inherit the flags.

Set the read-ony flag when accessed as the global catalog

Modify the LDAP server to track that this query is for the global
catalog (by incoming port), and set a opqaue pointer.

Next step is to read that opaque pointer in the partitions module.

Andrew Bartlett