Bug #26242 UPDATE with subquery and triggers failing with cluster tables

In certain cases AFTER UPDATE/DELETE triggers on NDB tables that referenced
subject table didn't see the results of operation which caused invocation
of those triggers. In other words AFTER trigger invoked as result of update
(or deletion) of particular row saw version of this row before update (or
deletion).

The problem occured because NDB handler in those cases postponed actual
update/delete operations to be able to perform them later as one batch.

This fix solves the problem by disabling this optimization for particular
operation if subject table has AFTER trigger for this operation defined.
To achieve this we introduce two new flags for handler::extra() method:
HA_EXTRA_DELETE_CANNOT_BATCH and HA_EXTRA_UPDATE_CANNOT_BATCH.
These are called if there exists AFTER DELETE/UPDATE triggers during a
statement that potentially can generate calls to delete_row()/update_row().
This includes multi_delete/multi_update statements as well as insert statements
that do delete/update as part of an ON DUPLICATE statement.

sql/sql_trigger.h

@@ -110,6 +110,11 @@ public:
                                 const char *old_table,
                                 const char *new_db,
                                 const char *new_table);
+  bool has_triggers(trg_event_type event_type, 
+                    trg_action_time_type action_time)
+  {
+    return (bodies[event_type][action_time]);
+  }
   bool has_delete_triggers()
   {
     return (bodies[TRG_EVENT_DELETE][TRG_ACTION_BEFORE] ||