MDEV-10507: MariaDB 10.1 + wsrep fails to start under systemd post-reboot

/var/run/mysqld must be created before wsrep recovery.

support-files/mariadb.service.in

@@ -59,6 +59,8 @@ ProtectHome=true
 # Execute pre and post scripts as root, otherwise it does it as User=
 PermissionsStartOnly=true
 
+@SYSTEMD_EXECSTARTPRE@
+
 # Perform automatic wsrep recovery. When server is started without wsrep,
 # galera_recovery simply returns an empty string. In any case, however,
 # the script is not expected to return with a non-zero status.
@@ -77,7 +79,6 @@ ExecStartPre=/bin/sh -c "[ ! -e /usr/bin/galera_recovery ] && VAR= || \
 # Use the [service] section and Environment="MYSQLD_OPTS=...".
 # This isn't a replacement for my.cnf.
 # _WSREP_NEW_CLUSTER is for the exclusive use of the script galera_new_cluster
-@SYSTEMD_EXECSTARTPRE@
 ExecStart=/usr/sbin/mysqld $MYSQLD_OPTS $_WSREP_NEW_CLUSTER $_WSREP_START_POSITION
 @SYSTEMD_EXECSTARTPOST@