Test cleanup and fix.

MDEV-18942: Json_writer::add_bool: Conditional jump or move depends on uninitialised value upon fulltext search under optimizer trace

For keyuse of fulltext set the value for null_rejecting to FALSE
as we don't add NOT NULL keys for fulltext keyuses

MDEV-18962: ASAN heap-buffer-overflow in Single_line_formatting_helper::on_add_str with optimizer trace

Fixed a typo

MariaDB does support InnoDB tables with no stored columns.
(They are necessarily empty.)

after commit b5615eff

On Microsoft Windows, InnoDB writes the path separator \ to the
redo log file, while on all other platforms, / is being used.

fil_name_parse(): Normalize the parsed path separators to the
native format. This allows backups or data sets to be portable
between Windows and other systems.

Closes #1225

MDEV-18921 Server crashes in bitmap_bits_set or bitmap_is_set upon UPDATE IGNORE .. FOR PORTION with binary logging

The fix is same as for MDEV-18859: initialize table->rpl_write_set in
FOR PORTION OF case.

MDEV-18859 Server crashes in bitmap_bits_set / pack_row / THD::binlog_write_row upon DELETE .. FOR PORTION with binary logging

rpl_write_set is initialized in TABLE::mark_columns_per_binlog_row_image.
Since we just call use_all_columns for PORTION OF case, no need in
column marking logic here. Instead, initialize table->rpl_write_set in
place.

The main problem was lack of proper QueryArena handling in
`period_setup_conds`. Since mysql_prepare_update/mysql_prepare_delete
are called during `PREPARE` statement, period conditions, should be
allocated on statement query arena.

Another problem is incorrect statement state handling in
period_setup_conds, which led to unexpected mysql_update termination.

* mysql_update: move period_setup_conds() to mysql_prepare_update to
  store conditions in statement's mem_root

* mtr: add period suite to default list, since --ps-protocol is now
  fixed

Fixes bugs:
MDEV-18853 Assertion `0' failed in Protocol::end_statement upon DELETE .. FOR PORTION via prepared statement
MDEV-18852 Server crashes in reinit_stmt_before_use upon UPDATE .. FOR PORTION via prepared statement

Closes #593

instant_alter_column_possible(): Do not support instantaneous removal
of NOT NULL if the table needs to be rebuilt for removing the hidden
FTS_DOC_ID column. This is not ideal and should ultimately be fixed
properly in MDEV-17459.

This basically is a duplicate of MDEV-18219, proving that the
assertion was not relaxed correctly.

dict_index_t::in_instant_init: A debug flag that will only be set in
btr_cur_instant_init_low() in order to suppress the assertion failure
in rec_init_offsets() for that code path only.

MDEV-18503 Assertion `native.length() == binlen' failed in Type_handler_timestamp_common::make_sort_key

Tests for MDEV-18595 Assertion `0' failed in Item_cache_timestamp::val_datetime_packed / Predicant_to_list_comparator::cmp_arg

The patch for MDEV-18240 fixed this problem earlier. Adding tests only.

This is follow-up for commit 619d22dd
to fix the cmake -DWITH_EMBEDDED_SERVER build.

Fixed by adding more rows to a table

Other things:
- Speed up index_merge tests 20% by adding begin/commit around loops that
  generated rows.

Fixed by caching last binary log number used in last_used_log_number

Other things:
- Moved locking of LOCK_log form new_file_impl() to new_file(). This fixed
  a bug where LOCK_log could have been unlocked even if 'need_lock' was
  not set.  Removed not anymore used argument need_lock.
- Made generate_new_name() virtual to simplify the code between
  other logs and binary log.

Reviewed by Andrei Elkin

On some systems with 10,000+ binlogs, show binary logs could block
log rotation for more than 10 seconds.

This patch fixes this by first caching all binary log names and
releases all mutexes while calculating the sizes of the binary logs.

Other things:
- Ensure that reinit_io_cache() sets end_of_file when moving to read_cache.
  This ensures that external changes of the underlying file is known to
  the cache.
- get_binlog_list() is made more efficent and show_binlogs() is changed
  to call get_binlog_list()

Reviewed by Andrei Elkin