MDEV-38618 Unused variable dict_table_t::fk_max_recusive_level

Ever since mysql/mysql-server@3777746
was applied in commit 2e814d4702d71a04388386a9f591d14a35980bfed
the data member dict_table_t::fk_max_recusive_level is never being
read, only initialized as 0. Let us follow the lead of
mysql/mysql-server@b22ac19
and remove this useless field.

Author: dr-m

storage/innobase/dict/dict0load.cc

@@ -2506,10 +2506,6 @@ static dict_table_t *dict_load_table_one(const span<const char> &name,
 		}
 	}
 
-	/* Initialize table foreign_child value. Its value could be
-	changed when dict_load_foreigns() is called below */
-	table->fk_max_recusive_level = 0;
-
 	/* We will load the foreign key information only if
 	all indexes were loaded. */
 	if (!table->is_readable()) {
@@ -2528,7 +2524,6 @@ static dict_table_t *dict_load_table_one(const span<const char> &name,
 			goto evict;
 		} else {
 			dict_mem_table_fill_foreign_vcol_set(table);
-			table->fk_max_recusive_level = 0;
 		}
 	}
 
@@ -3222,9 +3217,7 @@ dict_load_foreigns(
 	mtr.commit();
 
 	if ((sec_index = dict_table_get_next_index(sec_index))) {
-		/* Switch to scan index on REF_NAME, fk_max_recusive_level
-		already been updated when scanning FOR_NAME index, no need to
-		update again */
+		/* Switch to scan index on REF_NAME */
 		check_recursive = false;
 		goto start_load;
 	}

storage/innobase/include/dict0mem.h

@@ -2320,11 +2320,6 @@ struct dict_table_t {
 	/** Node of the LRU list of tables. */
 	UT_LIST_NODE_T(dict_table_t)		table_LRU;
 
-	/** Maximum recursive level we support when loading tables chained
-	together with FK constraints. If exceeds this level, we will stop
-	loading child table into memory along with its parent table. */
-	byte					fk_max_recusive_level;
-
   /** DDL transaction that last touched the table definition, or 0 if
   no history is available. This includes possible changes in
   ha_innobase::prepare_inplace_alter_table() and

storage/innobase/row/row0mysql.cc

@@ -1560,8 +1560,6 @@ init_fts_doc_id_for_ref(
 	dict_table_t*	table,		/*!< in: table */
 	ulint*		depth)		/*!< in: recusive call depth */
 {
-	table->fk_max_recusive_level = 0;
-
 	/* Limit on tables involved in cascading delete/update */
 	if (++*depth > FK_MAX_CASCADE_DEL) {
 		return;