mysql driver compile problem

[Christopher Carver]

Platform is Ubuntu Linux 6.06 server i386 with kernel version 2.6.15-23. 
Software is Freeradius 1.1.3 and MySQL 4.1.21.  The problem is that the
Freeradius configure script will not detect the existance of the mysqlclient_r
library and subsequently fails to build the rlm_sql_mysql driver despite my use
of the --with-mysql-lib-dir directive.

The configure line:
./configure --prefix=/usr/local/pw/freeradius-1.1.3
--with-mysql-lib-dir=/usr/local/lib/mysql

>From the configure output:
checking for mysql_init in -lmysqlclient_r (using mysql_config)... no
checking for mysql_init in -lmysqlclient_r... no
configure: WARNING: mysql libraries not found. Use --with-mysql-lib-dir=<path>.
checking for mysql.h (using mysql_config)... yes
configure: WARNING: sql submodule 'mysql' disabled
configure: creating ./config.status

A listing of the lib dir:
# ls -l /usr/local/lib/mysql/libmysqlclient_r*
-rw-r--r-- 1 root root 1462324 2006-11-14 02:23
/usr/local/lib/mysql/libmysqlclient_r.a
-rw-r--r-- 1 root root 1395548 2006-11-13 22:44
/usr/local/lib/mysql/libmysqlclient_r.so.15
-rw-r--r-- 1 root root 1395548 2006-11-13 22:44
/usr/local/lib/mysql/libmysqlclient_r.so.15.0.0

Some evidence of the existance of the referenced function in that library:
# file /usr/local/lib/mysql/libmysqlclient_r.so.15
/usr/local/lib/mysql/libmysqlclient_r.so.15: ELF 32-bit LSB shared object, Intel
80386, version 1 (SYSV), stripped
# strings /usr/local/lib/mysql/libmysqlclient_r.so.15 | grep mysql_init
mysql_init

Any ideas?

Thanks,

Chris Carver
Network Engineer