post push fix for BUG#37051

mysql-test/r/multi_update.result:
  update result
sql/sql_class.cc:
  Initialize table_map_for_update to 0

mysql-test/r/multi_update.result

@@ -627,7 +627,7 @@ a	b
 4	4
 show master status /* there must be the UPDATE query event */;
 File	Position	Binlog_Do_DB	Binlog_Ignore_DB
-master-bin.000001	197		
+master-bin.000001	206		
 delete from t1;
 delete from t2;
 insert into t1 values (1,2),(3,4),(4,4);
@@ -637,7 +637,7 @@ UPDATE t2,t1  SET t2.a=t2.b where t2.a=t1.a;
 ERROR 23000: Duplicate entry '4' for key 'PRIMARY'
 show master status /* there must be the UPDATE query event */;
 File	Position	Binlog_Do_DB	Binlog_Ignore_DB
-master-bin.000001	212		
+master-bin.000001	221		
 drop table t1, t2;
 set @@session.binlog_format= @sav_binlog_format;
 drop table if exists t1, t2, t3;

sql/sql_class.cc

@@ -514,6 +514,7 @@ THD::THD()
    lock_id(&main_lock_id),
    user_time(0), in_sub_stmt(0),
    binlog_table_maps(0), binlog_flags(0UL),
+   table_map_for_update(0),
    arg_of_last_insert_id_function(FALSE),
    first_successful_insert_id_in_prev_stmt(0),
    first_successful_insert_id_in_prev_stmt_for_binlog(0),