ITS#5378 delta-sync issues

[hyc@symas.com]

A fix is in HEAD. delta-syncrepl will now fallback to regular refresh in 
additional cases - LDAP_ALREADY_EXISTS, which may occur for old Adds,
LDAP_NO_SUCH_OBJECT, for cases already covered in ITS#5376,
LDAP_NO_SUCH_ATTRIBUTE, for old Modifies, and LDAP_TYPE_OR_VALUE_EXISTS
also for old Modifies. Pretty sure that covers all of the possible out-of-sync 
cases. Please test.
-- 
   -- Howard Chu
   CTO, Symas Corp.           http://www.symas.com
   Director, Highland Sun     http://highlandsun.com/hyc/
   Chief Architect, OpenLDAP  http://www.openldap.org/project/