MySQL: configure ::zaqar::db::mysql selectively

Adds the ability to create an empty MySQL database for Zaqar
if zaqar is enabled and settings for the mysql backend are
also available in hiera. This should allow Zaqar's database to
get created when needed, but skipped if MongoDB is used
instead (per overcloud defaults).

Change-Id: I3598e39c0a3cdf80b96e728d9aa8a7e6505e0690

manifests/profile/base/database/mysql.pp

@@ -217,6 +217,10 @@ class tripleo::profile::base::database::mysql (
     if hiera('ec2_api_enabled', false) {
       include ::ec2api::db::mysql
     }
+    if hiera('zaqar_enabled', false) and hiera('zaqar::db::mysql::user', '') == 'zaqar' {
+      # NOTE: by default zaqar uses mongodb
+      include ::zaqar::db::mysql
+    }
   }
 
 }