codership/mysql-wsrep#67 - total order isolation for FLUSH

The following FLUSH commands are now executed under total
order isolation:
* FLUSH DES_KEY_FILE
* FLUSH HOSTS
* FLUSH PRIVILEGES
* FLUSH QUERY CACHE
* FLUSH STATUS
* FLUSH USER_RESOURCES

This patch was backported from mysql-wsrep/5.6 commit
cdea608d9a27701d76d0deec49976aa0a08b1a56

Author: temeo

sql/sql_parse.cc

@@ -4119,6 +4119,21 @@ case SQLCOM_PREPARE:
       break;
     }
 
+#ifdef WITH_WSREP
+    if (lex->type & (
+            REFRESH_GRANT            |
+            REFRESH_HOSTS            |
+            REFRESH_DES_KEY_FILE     |
+#ifdef HAVE_QUERY_CACHE
+            REFRESH_QUERY_CACHE_FREE |
+#endif /* HAVE_QUERY_CACHE */
+            REFRESH_STATUS           |
+            REFRESH_USER_RESOURCES))
+    {
+      WSREP_TO_ISOLATION_BEGIN(WSREP_MYSQL_DB, NULL, NULL)
+    }
+#endif /* WITH_WSREP*/
+
     /*
       reload_acl_and_cache() will tell us if we are allowed to write to the
       binlog or not.