MDEV 13679 Enabled sequences to be used in DEFAULT

Other changes done to get this to work:
- Added 'internal_tables' to TABLE object to list which sequence tables
  is needed to use the table.
- Mark any expression using DEFAULT() with LEX->default_used.
  This is needed when deciding if we should open internal sequence
  tables when a table is opened (we don't need to open sequence tables
  if the main table is only used with SELECT).
- Create_and_open_temporary_table() can now also open all internal
  sequence tables.
- Added option MYSQL_LOCK_USE_MALLOC to mysql_lock_tables()
  to force memory allocation to be used with malloc instead of
  memroot.
- Added flag to MYSQL_LOCK to remember if allocation was done with
  malloc or memroot (makes code simpler and safer).
- init_one_table_for_prelocking() now takes argument for what lock to
  use instead of it's a routine or something else.
- Renamed prelocking placeholders to make them more understandable as
  they are now used in more code.
- Changed test in check_lock_and_start_stmt() if found table has correct
  locks. The old test didn't work for tables that has lock
  TL_WRITE_ALLOW_WRITE, which is what sequence tables are using.
- Added VCOL_NOT_VIRTUAL option to ensure that sequence functions can't
  be used with virtual columns
- More sequence tests

sql/sql_class.cc

@@ -4688,7 +4688,7 @@ TABLE *find_fk_open_table(THD *thd, const char *db, size_t db_len,
   {
     if (t->s->db.length == db_len && t->s->table_name.length == table_len &&
         !strcmp(t->s->db.str, db) && !strcmp(t->s->table_name.str, table) &&
-        t->pos_in_table_list->prelocking_placeholder == TABLE_LIST::FK)
+        t->pos_in_table_list->prelocking_placeholder == TABLE_LIST::PRELOCK_FK)
       return t;
   }
   return NULL;
@@ -6081,7 +6081,7 @@ int THD::decide_logging_format(TABLE_LIST *tables)
       replicated_tables_count++;
 
       if (table->lock_type <= TL_READ_NO_INSERT &&
-          table->prelocking_placeholder != TABLE_LIST::FK)
+          table->prelocking_placeholder != TABLE_LIST::PRELOCK_FK)
         has_read_tables= true;
       else if (table->table->found_next_number_field &&
                 (table->lock_type >= TL_WRITE_ALLOW_WRITE))