When building with mysql support the configure script bails out:
./configure --with-mysql=/usr/local --with-database-backend=mysql --prefix=/usr/local --mandir=/usr/local/man --infodir=/usr/local/info/ --build=i386-portbld-freebsd8
...
checking for database backend... MySQL
checking for mysql_config... /usr/local/bin/mysql_config
checking for mysql... /usr/local/bin/mysql
checking mysql version... 5.1.56
./configure: ${MYSQL_VERSION/...}: Bad substitution