MTR_COMBINATIONS contains comma-separated list of currently applied
combinations "x,y,...". MTR_COMBINATION_X, MTR_COMBINATION_Y, ... are
set to 1 for this list of combinations.

Fixed dead check: non-existent element $tinfo->{combination}.

Better use this clause:

use warnings FATAL => 'uninitialized';

But this must be very well tested.

Tests affected (forced mode):

main.type_timestamp

Tests affected (forced versioning):

rpl.rpl_row_merge_engine

Affected tests (forced mode):

main.index_merge_myisam

After optimization versioning AND takes operands from WHERE AND
leaving `select_lex->where` as empty dangling AND.

Affected tests (forced mode):

main.win
main.selectivity_innodb
main.subselect_cache
main.analyze_stmt_orderby

Related to #226 (909867d0).

Affected tests (forced mode): rpl.rpl_timezone

Affected tests (forced mode): binlog_encryption.encrypted_slave

Affected tests (forced mode): binlog_encryption.encrypted_slave

row_prebuilt_t::versioned_write: Cache the value of TABLE::versioned_write()
in ha_innobase::build_template()

Disabled DROP and SURVIVE modes.

THD::vers_update_trt, trx_t::vers_update_trt, trx_savept_t::vers_update_trt:
Remove. Instead, determine from trx_t::mod_tables whether versioned
columns were affected by the transaction.

handlerton::prepare_commit_versioned: Replaces vers_get_trt_data.
Return the transaction start ID and also the commit ID, in case
the transaction modified any system-versioned columns (0 if not).

TR_table::store_data(): Remove (merge with update() below).

TR_table::update(): Add the parameters start_id, end_id.

ha_commit_trans(): Remove a condition on SQLCOM_ALTER_TABLE.
If we need something special for ALTER TABLE...ALGORITHM=INPLACE,
that can be done inside InnoDB by modifying trx_t::mod_tables.

innodb_prepare_commit_versioned(): Renamed from innodb_get_trt_data().
Check trx_t::mod_tables to see if any changes to versioned columns
are present.

trx_mod_table_time_t: A pair of logical timestamps, replacing the
undo_no_t in trx_mod_tables_t. Keep track of not only the first
modification to a persistent table in each transaction, but also
the first modification of a versioned column in a table.

dtype_t, dict_col_t: Add the accessor is_any_versioned(), to check
if the type refers to a system-versioned user or system column.

upd_t::affects_versioned(): Check if an update affects a versioned
column.

trx_undo_report_row_operation(): If a versioned column is affected
by the update, invoke trx_mod_table_time_t::set_versioned().

trx_rollback_to_savepoint_low(): If all changes to versioned columns
were rolled back, invoke trx_mod_table_time_t::rollback_versioned(),
so that trx_mod_table_time_t::is_versioned() will no longer hold.

Both bits DATA_VERSIONED will be set in prtype if the column
is system-versioned. The bits will be 0 for normal unversioned
columns. For the special columns identifying the logical start
and end times of versions, only one bit will be set:
DATA_VERS_START or DATA_VERS_END.

create_table_info_t::create_table_def(),
prepare_inplace_alter_table_dict(): Set prtype |= DATA_VERSIONED
for system-versioned columns.

dfield_t::is_version_historical_end(): Determine if a data tuple
field is_version_end() and contains a timestamp in the past
(not TRX_ID_MAX).

dtype_t, dict_col_t: Add the accessors
is_versioned(), is_version_start(), is_version_end().

trx_id_max_bytes[]: The bit pattern of TRX_ID_MAX, for use with
memcmp().

Merge branch '10.3' into trunk

Related to #212.

Extra update of sys_trx_start removed [#87].

Windows platform is suffered with this problem.