Moved opt_for_system_time_clause from table identifier (which binds
it to single table) to table expression.

* BEGIN_TS(), COMMIT_TS() SQL functions;
* VTQ instead of packed stores secs + usecs like my_timestamp_to_binary() does;
* versioned SELECT to IB is translated with COMMIT_TS();
* SQL fixes:
  - FOR_SYSTEM_TIME_UNSPECIFIED condition compares to TIMESTAMP_MAX_VALUE;
  - segfault fix #36: multiple execute of prepared stmt;
  - different tables to same stored procedure fix (#39)
* Fixes of previous parts: ON DUPLICATE KEY, other misc fixes.

These features are defined only in XtraDB:
  chaged_page_bitmaps,
  innodb_changed_pages

* versioned DML: INSERT, UPDATE, DELETE;
* general refactoring and fixes.

Warning: breaks 'insert' and 'update' tests since they require part IV.

* moved vers_notify_vtq() to commit phase;
* low_level insert (load test passed);
* rest of SYS_VTQ columns filled: COMMIT_TS, CONCURR_TRX;
* savepoints support;
* I_S.INNODB_SYS_VTQ adjustments:
  - limit to I_S_SYS_VTQ_LIMIT(10000) of most recent records;
  - CONCURR_TRX limit to I_S_MAX_CONCURR_TRX(100) with '...' truncation marker;
  - TIMESTAMP fields show fractions of seconds.

* SYS_VTQ internal InnoDB table;
* I_S.INNODB_SYS_VTQ table;
* vers_notify_vtq(): add record to SYS_VTQ on versioned DML;
* SYS_VTQ columns filled: TRX_ID, BEGIN_TS.

Problem was that we got an error in sequence_insert while opening the
newly created sequence table in an prepared statement as the table id
didn't match.
Fixed by temporarly removing the reprepare observer during
sequence_insert as there can never be a table missmatch in this case.

storage/rocksdb/rdb_datadic.cc failed to compile on big endian machines (wrong usage of static_assert)

- Don't call my_chsize() for small (less than 64K) binary log tmp files
- Don't flush cache to disk on reset.

- Added file name to error in mysql-test-run
- When creating tags, first do it for sql to make it easier to find things in server

We introduce a NO_ROLLBACK flag for InnoDB tables. This flag only works
for tables that have a single index. Apart from undo logging, this flag
will also prevent locking and the assignment of DB_ROW_ID or DB_TRX_ID,
and imply READ UNCOMMITTED isolation. It is assumed that the SQL layer
is guaranteeing mutual exclusion.

After the initial insert of the single record during CREATE SEQUENCE,
InnoDB will be updating the single record in-place. This is crash-safe
thanks to the redo log. (That is, after a crash after CREATE SEQUENCE
was committed, the effect of sequence operations will be observable
fully or not at all.)

When it comes to the durability of the updates of SEQUENCE in
InnoDB, there is a clear analogy to MDEV-6076 Persistent AUTO_INCREMENT.
The updates would be made persistent by the InnoDB redo log flush
at transaction commit or rollback (or XA PREPARE), provided that
innodb_log_flush_at_trx_commit=1.

Similar to AUTO_INCREMENT, it is possible that the update of a SEQUENCE
in a middle of transaction becomes durable before the COMMIT/ROLLBACK of
the transaction, in case the InnoDB redo log is being flushed as a result
of the a commit or rollback of some other transaction, or as a result of
a redo log checkpoint that can be initiated at any time by operations that
are writing redo log.

dict_table_t::no_rollback(): Check if the table does not support rollback.

BTR_NO_ROLLBACK: Logging and locking flags for no_rollback() tables.

DICT_TF_BITS: Add the NO_ROLLBACK flag.

row_ins_step(): Assign 0 to DB_ROW_ID and DB_TRX_ID, and skip
any locking for no-rollback tables. There will be only a single row
in no-rollback tables (or there must be a proper PRIMARY KEY).

row_search_mvcc(): Execute the READ UNCOMMITTED code path for
no-rollback tables.

ha_innobase::external_lock(), ha_innobase::store_lock():
Block CREATE/DROP SEQUENCE in innodb_read_only mode.
This probably has no effect for CREATE SEQUENCE, because already
ha_innobase::create() should have been called (and refused)
before external_lock() or store_lock() is called.

ha_innobase::store_lock(): For CREATE SEQUENCE, do not acquire any
InnoDB locks, even though TL_WRITE is being requested. (This is just
a performance optimization.)

innobase_copy_frm_flags_from_create_info(), row_drop_table_for_mysql():
Disable persistent statistics for no_rollback tables.

"Unknown table" to "Unknown view"

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.