Auth ./configure --without-mysql should disable the gmysql module

[wojas]

• Program: Authoritative
• Issue type: Bug report

Short description

The gmysql module is built by default. I expected that --without-mysql would skip everything that requires mysql, but instead the configure script still checks for mysql and exits with an error.

Environment

• Operating system: Ubuntu 16.04
• Software version: master 1efb94e
• Software source: github

Steps to reproduce

1. ./configure --disable-mysql

Expected behaviour

Do not build any mysql modules.

Actual behaviour

The configure scripts do no properly check for the value 'no', which is set by --without-mysql:

checking for no/bin/mysql_config... configure: error: not found

[pieterlexis]

I think it will be better to throw an error with the essence of "MySQL is required by one or more of the (dyn-)modules, cannot disable MySQL support"

[wojas]

Maybe add "(see --with-modules and --with-dynmodules options)" to the message?