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_class.h

@@ -699,6 +699,7 @@ typedef struct system_variables
   ulong session_track_transaction_info;
   my_bool session_track_schema;
   my_bool session_track_state_change;
+  my_bool sequence_read_skip_cache;
 
   ulong threadpool_priority;
 } SV;
@@ -2215,6 +2216,8 @@ public:
     chapter 'Miscellaneous functions', for functions GET_LOCK, RELEASE_LOCK.
   */
   HASH ull_hash;
+  /* Hash of used seqeunces (for PREVIOUS value) */
+  HASH sequences;
 #ifndef DBUG_OFF
   uint dbug_sentry; // watch out for memory corruption
 #endif
@@ -2419,6 +2422,8 @@ private:
   uint binlog_table_maps;
 public:
   void issue_unsafe_warnings();
+  void reset_unsafe_warnings()
+  { binlog_unsafe_warning_flags= 0; }
 
   uint get_binlog_table_maps() const {
     return binlog_table_maps;
@@ -5689,6 +5694,14 @@ public:
   SP Bulk execution optimized
 */
 #define CF_SP_BULK_OPTIMIZED (1U << 20)
+/**
+  If command creates or drops a table
+*/
+#define CF_SCHEMA_CHANGE (1U << 21)
+/**
+  If command creates or drops a database
+*/
+#define CF_DB_CHANGE (1U << 22)
 
 /* Bits in server_command_flags */