[Dovecot] OpenLDAP only?

I tried to compile Dovecot v1.0RC2 on Opeteron/Solaris 10 box.

"db-ldap.c", line 343: undefined symbol: LDAP_SASL_QUIET

"LDAP_SASL_QUIET" is defined as "2U" in OpenLDAP's ldap.h but not in /usr/include/ldap.h

How can I compile Dovecot with Sun's LDAP implementation?