systemd: deprecate MYSQLD_OPTS

It was added without a good use case as
all MariaDB options where available to
uses to put in configuration files.

Put a notice of deprecation for now.

Author: grooverdan

support-files/mariadb.service.in

@@ -66,9 +66,8 @@ ProtectHome=true
 # ExecStartPre=@scriptdir@/mariadb-install-db
 
 # Start main service
-# MYSQLD_OPTS here is for users to set in /etc/systemd/system/mariadb.service.d/MY_SPECIAL.conf
-# Use the [Service] section and Environment="MYSQLD_OPTS=...".
-# This isn't a replacement for my.cnf.
+# MYSQLD_OPTS as a user environment variable is deprecated.
+# Please put equivalent configuration in the MariaDB configuration files.
 ExecStart=@sbindir@/mariadbd $MYSQLD_OPTS
 
 @SYSTEMD_EXECSTARTPOST@