* gnu/services/databases.scm (<mysql-configuration>): Add AUTO-UPGRADE? field.
(mysql-upgrade-wrapper, mysql-upgrade-shepherd-service,
mysql-shepherd-services): New variables.
(mysql-service-type): Use MYSQL-SHEPHERD-SERVICES instead of
MYSQL-SHEPHERD-SERVICE.
* doc/guix.texi (Database Services): Document the AUTO-UPGRADE? field of
MYSQL-SERVICE-TYPE.
* gnu/tests/databases.scm (run-mysql-test): Test that mysql_upgrade has run.