set LDAP_OPT_REFERRALS option as LDAP_OPT_OFF.

Some of LDAP servers return 'Search failed' w/ LDAP_OPT_REFERRALS is LDAP_OPT_ON.
And many LDAP clients are also disabling follow referrals option.

I wanna set off this option also in InspIRCd.

Thank you.