Mistakes corrected.

TVC can be used in IN subquery and in PARTITION BY struct now.
Special variable to control working of optimization added.

sql/sql_lex.h

@@ -1012,6 +1012,7 @@ public:
   thr_lock_type lock_type;
   
   table_value_constr *tvc;
+  bool in_tvc;
 
   void init_query();
   void init_select();