For future reference/backup purposes, here's the config line we're using for dspam:
./configure --with-dspam-home=/var/dspam --with-delivery-agent=/usr/local/bin/maildrop --sysconfdir=/etc --enable-debug --with-storage-driver=mysql_drv --enable-virtual-users --with-mysql-includes=/usr/include/mysql --with-mysql-libraries=/usr/lib/mysql --enable-preferences-extension