Enable hook for altering geo IP match logic.

@killua99 what are the reasons why this issue needs work? Is it in need of a review only or do you notice any issues with the patch?

I forgot about that, to tell why need work and I won't thing is needed.

Because the patch is a hack, to solve a situation about a thirdparty module. It add just a simple function to create a custom module to alter that variable. It should be handle for that module directly. If that guy will create a custom module to handle IP then why not submit that code on the thirdparty module that we're waiting for?

I disagree. I think we can add this patch to the module, but I recommend that we name the hook "eu_cookie_compliance_geoip_match"

I does however need an additional `eu_cookie_compliance.api.php` file to describe the alter hook.

Here's a complete patch, with the necessary api documentation.