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

mysql-test/suite/sql_sequence/default.test

@@ -0,0 +1,111 @@
+#
+# Testing sequence in DEFAULT clause
+#
+--source include/have_sequence.inc
+
+drop table if exists t1,s1,s2;
+drop view if exists v1;
+
+--echo #
+--echo # Test DEFAULT
+--echo #
+
+CREATE SEQUENCE s1 nocache engine=myisam;
+CREATE table t1 (a int default next value for s1, b int);
+show create table t1;
+insert into t1 SET b=1;
+insert into t1 SET b=2;
+insert into t1 (b) values (3),(4);
+select * from t1;
+update t1 set b=5 where a=1;
+delete from t1 where b=1;
+select * from t1;
+
+--echo #
+--echo # Executing DEFAULT function
+--echo #
+
+INSERT into t1 values(default(a),10);
+INSERT into t1 values(default(a),default(a));
+update t1 set a=default(a), b=12 where b=2;
+select * from t1;
+select default(a), a, b from t1;
+select * from s1;
+select * from t1 where default(a) > 0;
+select * from s1;
+
+--echo #
+--echo # View
+--echo #
+
+create view v1 as select * from t1;
+insert into v1 set b=20;
+select * from v1;
+drop view v1;
+
+--echo #
+--echo # Alter table
+--echo #
+
+CREATE SEQUENCE s2 nocache engine=myisam;
+alter table t1 add column c int default next value for s2, add column d int default previous value for s2;
+show create table t1;
+select * from t1;
+drop sequence s2;
+show create table t1;
+drop table t1;
+drop sequence s1;
+
+--echo #
+--echo # LOCK TABLES
+--echo #
+
+CREATE SEQUENCE s1 nocache engine=myisam;
+CREATE table t1 (a int default next value for s1, b int);
+insert into t1 (b) values (3),(4);
+LOCK TABLE t1 WRITE;
+--error ER_TABLE_NOT_LOCKED
+insert into t1 (b) values (5),(6);
+UNLOCK TABLES;
+
+LOCK TABLE t1 WRITE, s1 WRITE;
+insert into t1 (b) values (5),(6);
+select default(a) from t1;
+UNLOCK TABLES;
+
+LOCK TABLE t1 READ;
+--error ER_TABLE_NOT_LOCKED
+insert into t1 (b) values (5),(6);
+--error ER_TABLE_NOT_LOCKED
+select default(a) from t1;
+UNLOCK TABLES;
+
+LOCK TABLE t1 READ, s1 read;
+--error ER_TABLE_NOT_LOCKED_FOR_WRITE
+insert into t1 (b) values (5),(6);
+--error ER_TABLE_NOT_LOCKED_FOR_WRITE
+select default(a) from t1;
+UNLOCK TABLES;
+
+drop table t1;
+drop sequence s1;
+
+--echo #
+--echo # Wrong usage of default
+--echo #
+
+--error ER_NO_SUCH_TABLE
+CREATE table t1 (a int default next value for s1, b int);
+CREATE SEQUENCE s1 nocache engine=myisam;
+CREATE table t1 (a int default next value for s1, b int);
+DROP SEQUENCE s1;
+--error ER_NO_SUCH_TABLE
+insert into t1 (b) values (5),(6);
+--error ER_NO_SUCH_TABLE
+ALTER TABLE t1 add column c int;
+CREATE SEQUENCE s1 nocache engine=myisam;
+ALTER TABLE t1 add column c int;
+--error ER_NO_SUCH_TABLE
+ALTER TABLE t1 add column d int default next value for s_not_exits;
+drop table t1;
+drop sequence s1;