How can I know what configure options were used to compile it?

You can see the configure options using the mysqlbug command-line utility.

In your shell type mysqlbug and you'll see a template e-mail for bug submission.
At the bottom end of that e-mail you can see the configure line with all the options your copy of MySQL was compiled with.

Reference: http://serverfault.com/questions/62212/configure-options-mysql-server-was-compiled-with