openldap: upgrade to 2.4.43

1. Upgrade openldap from 2.4.42 to 2.4.43
2. Delete patch file openldap-fix-CVE-2015-6908.patch
because the bug(ITS#8240) has been fixed in OpenLDAP 2.4.43

http://www.openldap.org/software/release/changes.html



Signed-off-by: Fan Xin <fan.xin@jp.fujitsu.com>
Signed-off-by: Martin Jansa <Martin.Jansa@gmail.com>