MDEV-26575 Crash on shutdown after starting an XA transaction

Disallow XA when Galera library is loaded.
Reviewed-by: Jan Lindström <jan.lindstrom@mariadb.com>

mysql-test/suite/galera/r/MDEV-26575.result

+connection node_2;
+connection node_1;
+connection node_1;
+connection node_2;
+connection node_2;
+SET SESSION wsrep_on = OFF;
+XA START 'xatest';
+ERROR 42000: This version of MariaDB doesn't yet support 'XA transactions with Galera replication'

mysql-test/suite/galera/t/MDEV-26575.test

+#
+# MDEV-26575 Server crashes when execute shutdown statement after
+# starting an XA transaction
+#
+
+--source include/galera_cluster.inc
+
+# Save original auto_increment_offset values.
+--let $node_1=node_1
+--let $node_2=node_2
+--source include/auto_increment_offset_save.inc
+
+--connection node_2
+SET SESSION wsrep_on = OFF;
+--error ER_NOT_SUPPORTED_YET
+XA START 'xatest';
+--source include/restart_mysqld.inc
+
+--source include/auto_increment_offset_restore.inc

sql/sql_parse.cc

@@ -6047,7 +6047,7 @@ mysql_execute_command(THD *thd)
   }
   case SQLCOM_XA_START:
 #ifdef WITH_WSREP
-    if (WSREP(thd))
+    if (WSREP_ON)
     {
       my_error(ER_NOT_SUPPORTED_YET, MYF(0),
                "XA transactions with Galera replication");