For Item name_const , we should never do typecast it to Item_field because we
always expect it to be a constant value.
So instead of checking the type() its better to introduce a function in the
Item class get_item_field, which would return the item_field object for the item
which have type of FIELD_ITEM

This was introduced by two pointers I added to TRN
as part of MDEV-16421 Make system tables crash safe

- Added code to ensure that trn_prev is not pointing
  to wrong object
- A lot of new asserts and more code comments
- Simplified code in _ma_trnman_end_trans_hook()
  - New back link allowed me to remove a loop

Changed bootstrap scripts, adjusted result files.

Amend commit b853b4fd
that was reverted in commit 29150e23.

recv_parse_log_recs(): Do check for corrupted redo log or file
system before checking for len==0, but only read *ptr if
it is not past the end of the buffer (end_ptr).

recv_parse_log_rec(): Report incorrect redo log type
in a consistent way with recv_parse_or_apply_log_rec_body().
This is a follow-up to commit f30c5af4.

The Pool poisoning that was introduced in MDEV-15030 introduced
race conditions in AddressSanitizer builds, because concurrent
poisoning and unpoisoning were not prevented by any synchronization
primitive.

Pool::get(): Protect the unpoisoning by m_lock_strategy.

Pool::mem_free(): Protect the poisoning by m_lock_strategy.

Pool::putl(): Renamed from put(), because now the caller is
responsible for invoking m_lock_strategy.

If trx_free() and trx_create_low() were called while a call to
trx_reference() was pending, we could get a reference to a wrong
transaction object.

trx_reference(): Return NULL if the trx->id no longer matches.

lock_trx_release_locks(): Assign trx->id = 0, so that trx_reference()
will not return a reference to this object.

trx_cleanup_at_db_startup(): Assign trx->id = 0.

assert_trx_is_free(): Assert !trx->n_ref. Assert trx->id == 0,
now that it will be cleared as part of a transaction commit.

Also, replace reverse iteration with forward iteration.

lock_table_has(): Remove a redundant condition.

Allocate trx->lock.rec_pool and trx->lock.table_pool directly from trx_t.
Remove unnecessary use of std::vector.

In order to do this, move some definitions from lock0priv.h to
lock0types.h, so that ib_lock_t will not be an opaque type.

The patch for MDEV-16928 added a few new asserts to check that
time, date, datetime values are valid and consistent after initialization.
One of the new asserts caught an improper initialization in
Time::make_from_datetime_with_days_diff()
(the former function calc_datetime_days_diff()).
If the YYYYMM part is not zero after unpack time
we have an out-of-range TIME value.

Fixing the bug (in the code from MDEV-16910)

row_log_table_get_pk_col(): Replace a condition that was inadvertently
removed in MDEV-16365. PRIMARY KEY columns are never allowed to be NULL,
and failure to enforce the constraint caused a null pointer to be
dereferenced in mem_heap_dup().

Make all system tables in mysql directory of type
engine=Aria

Privilege tables are using transactional=1
Statistical tables are using transactional=0, to allow them
to be quickly updated with low overhead.
Help tables are also using transactional=0 as these are only
updated at init time.

Other changes:
- Aria store engine is now a required engine
- Update comment for Aria tables to reflect their new usage
- Fixed that _ma_reset_trn_for_table() removes unlocked table
  from transaction table list. This was needed to allow one
  to lock and unlock system tables separately from other
  tables, for example when reading a procedure from mysql.proc
- Don't give a warning when using transactional=1 for engines
  that is using transactions. This is both logical and also
  to avoid warnings/errors when doing an alter of a privilege
  table to InnoDB.
- Don't abort on warnings from ALTER TABLE for changes that
  would be accepted by CREATE TABLE.
- New created Aria transactional tables are marked as not movable
  (as they include create_rename_lsn).
- bootstrap.test was changed to kill orignal server, as one
  can't anymore have two servers started at same time on same
  data directory and data files.
- Disable maria.small_blocksize as one can't anymore change
  aria block size after system tables are created.
- Speed up creation of help tables by using lock tables.
- wsrep_sst_resync now also copies Aria redo logs.

aws_key_management needs current directory to be datadir during
initalization, it scans current directory for encrypted keys.

Fix is to ensure, that plugin initialization in mariabackup happens
after the call to my_setwd(mysql_real_data_home).

The problem occurs because the statement generated by Spider used an
internal function name, ADD_TIME.

This problem has been corrected by the fix for bug MDEV-16878 within the
server, which enables Spider to generate the statement using the actual
SQL function name.  I have made some additional changes within Spider to fix
related problems that I observed while testing.

Author:
  Jacob Mathew.

First Reviewer:
  Alexander Barkov.

Second Reviewer:
  Kentoku Shiba.

Cherry-Picked:
  Commit 4b6dccc8 on branch bb-10.3-MDEV-16398

The problem occurs because the statement generated by Spider used an
internal function name, ADD_TIME.

This problem has been corrected by the fix for bug MDEV-16878 within the
server, which enables Spider to generate the statement using the actual
SQL function name.  I have made some additional changes within Spider to fix
related problems that I observed while testing.

Author:
  Jacob Mathew.

First Reviewer:
  Alexander Barkov.

Second Reviewer:
  Kentoku Shiba.

Merged:
  Commit 4b6dccc8 on branch bb-10.3-MDEV-16398

Fix a race condition in the test.

This will change the InnoDB encrypted redo log format only.
Unencrypted redo log will keep using the MariaDB 10.3 format.
In the new encrypted redo log format, 4 additional bytes will
be reserved in the redo log block trailer for storing the
encryption key version.

For performance reasons, the encryption key rotation
(checking if the latest encryption key version is being used)
is only done at log_checkpoint().

LOG_HEADER_FORMAT_CURRENT: Remove.

LOG_HEADER_FORMAT_ENC_10_4: The encrypted 10.4 format.

LOG_BLOCK_KEY: The encryption key version field.

LOG_BLOCK_TRL_SIZE: Remove.

log_t: Add accessors framing_size(), payload_size(), trailer_offset(),
to be used instead of referring to LOG_BLOCK_TRL_SIZE.

log_crypt_t: An operation passed to log_crypt().

log_crypt(): Perform decryption, encryption, or encryption with key
rotation. Return an error if key rotation at decryption fails.
On encryption, keep using the previous key if the rotation fails.
At startup, old-format encrypted redo log may be written before
the redo log is upgraded (rebuilt) to the latest format.

log_write_up_to(): Add the parameter rotate_key=false.

log_checkpoint(): Invoke log_write_up_to() with rotate_key=true.

The test causes simulated server crashes with DBUG_SUICIDE();.

It also relies on transactions that were committed right before the
crash to be visible after the crash (that is, it requires durability).

Run the test with transaction durability enabled: set
rocksdb-flush-log-at-trx-commit=1.

only run git if .git exists, don't do it for source tarballs

we stopped using -fno-implicit-templates many years ago