Toolkits are able declare their requirements

In #1069140: Requirements should be provided by image toolkit → , Drupal core will fix the actual situation where the image toolkit requirements (admin/reports/status) are hardcoded only for GD2 toolkit. This issue is just to inform the module maintainer about this fix.

After that commit, toolkits will be able to provide their requirements by implementing a function

function image_TOOLKIT_ID_get_requirements() {
  ...
}

This function will return an associative array in the same format as the return array of hook_requirements(). See the new image_gd_get_requirements() for an example.

This D7 core fix doesn't affect the way the actual contributed toolkit works.