Hi Michael,
locate mysql This will show you where mysql is installed. For example, when I type it, I get this response: mysql: /usr/bin/mysql
That will be your mysql client, yes. But you don't need that to build php with mysql.
IIRC, php wants the mysql *libraries*, which are either in mysql-shared or mysql-devel rpm. I suspect the Cobalt pkg will install whatever is necessary to install php with mysql support, but you don't point the configure script at /usr/bin/mysql.
Unless I misunderstood you, of course. ;-) Bye... Nico