dsdb: Do checks for invalid renames in samldb, before repl_meta_data

dsdb: Do checks for invalid renames in samldb, before repl_meta_data

This ensures that conflict objects can be created in CN=System, and
that we do not stop replication just because some other DC allowed a
rename we do not like.

This is achived by doing the work in the samldb module, which is above
repl_meta_data in the stack.

Andrew Bartlett

Change-Id: I8c1a7d3e0fbd5a470cf1326cc055044ca885f7d9
Signed-off-by: Andrew Bartlett <abartlet@samba.org>
Reviewed-by: Guenter Kukkukk <kukks@samba.org>
Tested-by: Guenter Kukkukk <kukks@samba.org>