MDEV-10139 Support for SEQUENCE objects

Working features:
CREATE OR REPLACE [TEMPORARY] SEQUENCE [IF NOT EXISTS] name
    [ INCREMENT [ BY | = ] increment ]
    [ MINVALUE [=] minvalue | NO MINVALUE ]
    [ MAXVALUE [=] maxvalue | NO MAXVALUE ]
    [ START [ WITH | = ] start ] [ CACHE [=] cache ] [ [ NO ] CYCLE ]
    ENGINE=xxx COMMENT=".."
SELECT NEXT VALUE FOR sequence_name;
SELECT NEXTVAL(sequence_name);
SELECT PREVIOUS VALUE FOR sequence_name;
SELECT LASTVAL(sequence_name);

SHOW CREATE SEQUENCE sequence_name;
SHOW CREATE TABLE sequence_name;
CREATE TABLE sequence-structure ... SEQUENCE=1
ALTER TABLE sequence RENAME TO sequence2;
RENAME TABLE sequence TO sequence2;
DROP [TEMPORARY] SEQUENCE  [IF EXISTS] sequence_names

Missing features
- SETVAL(value,sequence_name), to be used with replication.
- Check replication, including checking that sequence tables are marked
  not transactional.
- Check that a commit happens for NEXT VALUE that changes table data (may
  already work)
- ALTER SEQUENCE. ANSI SQL version of setval.
- Share identical sequence entries to not add things twice to table list.
- testing insert/delete/update/truncate/load data
- Run and fix Alibaba sequence tests (part of mysql-test/suite/sql_sequence)
- Write documentation for NEXT VALUE / PREVIOUS_VALUE
- NEXTVAL in DEFAULT
  - Ensure that NEXTVAL in DEFAULT uses database from base table
- Two NEXTVAL for same row should give same answer.
- Oracle syntax sequence_table.nextval, without any FOR or FROM.
- Sequence tables are treated as 'not read constant tables' by SELECT; Would
  be better if we would have a separate list for sequence tables so that
  select doesn't know about them, except if refereed to with FROM.

Other things done:
- Improved output for safemalloc backtrack
- frm_type_enum changed to Table_type
- Removed lex->is_view and replaced with lex->table_type. This allows
  use to more easy check if item is view, sequence or table.
- Added table flag HA_CAN_TABLES_WITHOUT_ROLLBACK, needed for handlers
  that want's to support sequences
- Added handler calls:
 - engine_name(), to simplify getting engine name for partition and sequences
 - update_first_row(), to be able to do efficient sequence implementations.
 - Made binlog_log_row() global to be able to call it from ha_sequence.cc
- Added handler variable: row_already_logged, to be able to flag that the
  changed row is already logging to replication log.
- Added CF_DB_CHANGE and CF_SCHEMA_CHANGE flags to simplify
  deny_updates_if_read_only_option()
- Added sp_add_cfetch() to avoid new conflicts in sql_yacc.yy
- Moved code for add_table_options() out from sql_show.cc::show_create_table()
- Added String::append_longlong() and used it in sql_show.cc to simplify code.
- Added extra option to dd_frm_type() and ha_table_exists to indicate if
  the table is a sequence. Needed by DROP SQUENCE to not drop a table.

sql/sql_truncate.cc

@@ -216,7 +216,7 @@ Sql_cmd_truncate_table::handler_truncate(THD *thd, TABLE_LIST *table_ref,
       or writing into the table. Yet, to open a write cursor we need
       a thr_lock lock. Allow to open base tables only.
     */
-    table_ref->required_type= FRMTYPE_TABLE;
+    table_ref->required_type= TABLE_TYPE_NORMAL;
     /*
       Ignore pending FLUSH TABLES since we don't want to release
       the MDL lock taken above and otherwise there is no way to
@@ -248,8 +248,8 @@ Sql_cmd_truncate_table::handler_truncate(THD *thd, TABLE_LIST *table_ref,
     table_ref->table->file->print_error(error, MYF(0));
     /*
       If truncate method is not implemented then we don't binlog the
-      statement. If truncation has failed in a transactional engine then also we
-      donot binlog the statment. Only in non transactional engine we binlog
+      statement. If truncation has failed in a transactional engine then also
+      we don't binlog the statment. Only in non transactional engine we binlog
       inspite of errors.
      */
     if (error == HA_ERR_WRONG_COMMAND ||
@@ -311,14 +311,17 @@ bool Sql_cmd_truncate_table::lock_table(THD *thd, TABLE_LIST *table_ref,
   }
   else
   {
+    handlerton *hton;
+    bool is_sequence;
+
     /* Acquire an exclusive lock. */
     DBUG_ASSERT(table_ref->next_global == NULL);
     if (lock_table_names(thd, table_ref, NULL,
                          thd->variables.lock_wait_timeout, 0))
       DBUG_RETURN(TRUE);
 
-    handlerton *hton;
-    if (!ha_table_exists(thd, table_ref->db, table_ref->table_name, &hton) ||
+    if (!ha_table_exists(thd, table_ref->db, table_ref->table_name,
+                         &hton, &is_sequence) ||
         hton == view_pseudo_hton)
     {
       my_error(ER_NO_SUCH_TABLE, MYF(0), table_ref->db, table_ref->table_name);
@@ -337,7 +340,7 @@ bool Sql_cmd_truncate_table::lock_table(THD *thd, TABLE_LIST *table_ref,
       *hton_can_recreate= false;
     }
     else
-      *hton_can_recreate= hton->flags & HTON_CAN_RECREATE;
+      *hton_can_recreate= !is_sequence && hton->flags & HTON_CAN_RECREATE;
   }
 
   /*