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_lex.cc

@@ -196,8 +196,9 @@ init_lex_with_single_table(THD *thd, TABLE *table, LEX *lex)
   lex_start(thd);
   context->init();
   if ((!(table_ident= new Table_ident(thd,
+                                      &table->s->db,
                                       &table->s->table_name,
-                                      &table->s->db, TRUE))) ||
+                                      TRUE))) ||
       (!(table_list= select_lex->add_table_to_list(thd,
                                                    table_ident,
                                                    NULL,
@@ -737,6 +738,7 @@ void LEX::start(THD *thd_arg)
   spcont= NULL;
   proc_list.first= 0;
   escape_used= FALSE;
+  default_used= FALSE;
   query_tables= 0;
   reset_query_tables_list(FALSE);
   expr_allows_subselect= TRUE;
@@ -3025,7 +3027,7 @@ LEX::LEX()
   : explain(NULL),
     result(0), arena_for_set_stmt(0), mem_root_for_set_stmt(0),
     option_type(OPT_DEFAULT), context_analysis_only(0), sphead(0),
-    is_lex_started(0), limit_rows_examined_cnt(ULONGLONG_MAX)
+    default_used(0), is_lex_started(0), limit_rows_examined_cnt(ULONGLONG_MAX)
 {
 
   init_dynamic_array2(&plugins, sizeof(plugin_ref), plugins_static_buffer,