table_count was present twice in one class of LEX.

Remove table_count from Query_tables_list (not used, moved to MYSQL_LOCK).

Rename table_count from LEX to avoid mixing it with other counters of tables.

sql/sql_lex.h

@@ -1537,15 +1537,6 @@ class Query_tables_list
   Sroutine_hash_entry **sroutines_list_own_last;
   uint sroutines_list_own_elements;
 
-  /**
-    Number of tables which were open by open_tables() and to be locked
-    by lock_tables().
-    Note that we set this member only in some cases, when this value
-    needs to be passed from open_tables() to lock_tables() which are
-    separated by some amount of code.
-  */
-  uint table_count;
-
    /*
     These constructor and destructor serve for creation/destruction
     of Query_tables_list instances which are used as backup storage.
@@ -3060,7 +3051,7 @@ struct LEX: public Query_tables_list
     stores total number of tables. For LEX representing multi-delete
     holds number of tables from which we will delete records.
   */
-  uint table_count;
+  uint table_count_update;
   uint8 describe;
   bool  analyze_stmt; /* TRUE<=> this is "ANALYZE $stmt" */
   bool  explain_json;

sql/sql_parse.cc

@@ -4758,7 +4758,7 @@ mysql_execute_command(THD *thd)
     if (likely(!thd->is_fatal_error))
     {
       result= new (thd->mem_root) multi_delete(thd, aux_tables,
-                                               lex->table_count);
+                                               lex->table_count_update);
       if (likely(result))
       {
         if (unlikely(select_lex->vers_setup_conds(thd, aux_tables)))
@@ -9532,12 +9532,12 @@ bool multi_delete_set_locks_and_link_aux_tables(LEX *lex)
   TABLE_LIST *target_tbl;
   DBUG_ENTER("multi_delete_set_locks_and_link_aux_tables");
 
-  lex->table_count= 0;
+  lex->table_count_update= 0;
 
   for (target_tbl= lex->auxiliary_table_list.first;
        target_tbl; target_tbl= target_tbl->next_local)
   {
-    lex->table_count++;
+    lex->table_count_update++;
     /* All tables in aux_tables must be found in FROM PART */
     TABLE_LIST *walk= multi_delete_table_match(lex, target_tbl, tables);
     if (!walk)

sql/sql_prepare.cc

@@ -1446,7 +1446,7 @@ static int mysql_test_update(Prepared_statement *stmt,
     DBUG_ASSERT(update_source_table || table_list->view != 0);
     DBUG_PRINT("info", ("Switch to multi-update"));
     /* pass counter value */
-    thd->lex->table_count= table_count;
+    thd->lex->table_count_update= table_count;
     /* convert to multiupdate */
     DBUG_RETURN(2);
   }

sql/sql_update.cc

@@ -365,7 +365,7 @@ int mysql_update(THD *thd,
     DBUG_ASSERT(update_source_table || table_list->view != 0);
     DBUG_PRINT("info", ("Switch to multi-update"));
     /* pass counter value */
-    thd->lex->table_count= table_count;
+    thd->lex->table_count_update= table_count;
     /* convert to multiupdate */
     DBUG_RETURN(2);
   }
@@ -1710,7 +1710,7 @@ int mysql_multi_update_prepare(THD *thd)
   TABLE_LIST *table_list= lex->query_tables;
   TABLE_LIST *tl;
   Multiupdate_prelocking_strategy prelocking_strategy;
-  uint table_count= lex->table_count;
+  uint table_count= lex->table_count_update;
   DBUG_ENTER("mysql_multi_update_prepare");
 
   /*