openldap library and LDAP_OPT_X_KEEPALIVE_IDLE

Hello, Could someone tell which openldap library version first included keepalive paches giving acces to following options : LDAP_OPT_X_KEEPALIVE_IDLE LDAP_OPT_X_KEEPALIVE_PROBES LDAP_OPT_X_KEEPALIVE_INTERVAL

I have submitted a patch on freeradius for the rlm_ldap module for using those options to solve firewall/load-balancers LDAP session timeout by generation regular tcp keepalive packets ont LDAP sockets, and I see my current linux distros does not seems to have fresh-enough openldap library version to support this. debian squeeze libldap2-dev 2.4.17 CentOS 5.4 openldap-devel-2.3.43-3.el5 2.3.43

Best regards Fred MAISON