MDEV-12632: Source and destination overlap in memcpy, encryption.innodb-discard-import-change fails in buildbot with valgrind

Problem was that if tablespace was encrypted we try to copy
also page 0 from read buffer to write buffer that are in
that case the same memory area.

fil_iterate
	When tablespace is encrypted or compressed its
        first page (i.e. page 0) is not encrypted or
	compressed and there is no need to copy buffer.

Wait until rotation has ended and shutdown before grep to make sure
that dirty pages are on datafiles.

row_undo_step(): If innodb_fast_shutdown=3 has been requested,
abort the rollback of any non-DDL transactions. Starting with
MDEV-12323, we aborted the rollback of recovered transactions. The
transactions would be rolled back on subsequent server startup.

trx_roll_report_progress(): Renamed from trx_roll_must_shutdown(),
now that the shutdown check has been moved to the only caller.

trx_commit_low(): Allow mtr=NULL for transactions that are aborted
on rollback.

trx_rollback_finish(): Clean up aborted transactions to avoid
assertion failures and memory leaks on shutdown. This code was
previously in trx_rollback_active().

trx_rollback_to_savepoint_low(), trx_rollback_for_mysql_low():
Remove some redundant assertions.

Also, shorten the test so it usually runs 2 seconds, not 3.

numerous fixes for CREATE ... SELECT with system versioning:
In CREATE ... SELECT the table is created based on the result set,
field properties do not count. That is
* field invisibility is *not* copied over
* AS ROW START/END is *not* copied over
* the history is *not* copied over
* system row_start/row_end fields can *not* be created from the SELECT part

[closes tempesta-tech#472]

MDEV-15391 Server crashes in JOIN::fix_all_splittings_in_plan or Assertion `join->best_read < double(1.79...e+308L)' failed

vers_setup_conds() used to AND all conditions on row_start/row_end
columns and store it either in the WHERE clause or in the ON
clause for some table. In some cases this caused ON clause
to have conditions for tables that aren't part of that ON's join.

Fixed to put a table's condition always in the ON clause of the
corresponding table.

Removed unnecessary ... `OR row_end IS NULL` clause, it's not needed
in the ON clause.

Simplified handling on PS and SP.

fix parsing of the AS OF clause

get_schema_column_record(): print 'WITHOUT SYSTEM VERSIONING` in 'EXTRA'
for such fields

--gdb now accepts an argument, it will be passed to gdb as a command.
multiple commands can be separated by a (non-standard and not escapable)
delimiter - semicolon (;).

Old usage with a bare --gdb continues to work too, of course.

disallow system versioning for tables in mysql database

use named methods instead.

the function xxx_eq(a,b) returns true if two elements
are equal and false if they are not.

strmake_buf() macro should only be used with char[] arrays,
and never with char* pointers. To distinguish between the two
we create a new variable of the same type and initialize it
using array initializer, this causes compilation failure
with pointers. The variable is unused and will be removed by the
compiler. It's enough to do this check only with gcc, so
it doesn't have to be portable.

(will be added back when it'll be used)

remove dead code

Merge pull request #667

srv_purge_should_exit(): Remove the parameter n_purged.
If we happened to have n_purged==0 while some transaction was still
active, and then that transaction was added to the history list,
we were prematurely stopping the purge. It is more appropriate to
first check for trx_sys.any_active_transactions() == 0
(this count can only decrease during shutdown) and then for
trx_sys.history_size() == 0 (that count typically decreases, but
can increase when any remaining active transactions are committed
or rolled back).

innodb.dml_purge: Remove a server restart, and explicitly wait for
purge, and use FLUSH TABLE FOR EXPORT to read the file contents.
This will make the test run faster, easier to debug, and also
allow it to run with --embedded. This might also help repeat
MDEV-11802 better. The issue MDEV-13603 remains will remain tested
by innodb.table_flags.

purge_sys_t::n_submitted: Document that it is only accessed by
srv_purge_coordinator_thread.

purge_sys_t::n_completed: Exclusively use my_atomic access.

srv_task_execute(): Simplify the code.

srv_purge_coordinator_thread(): Test the cheaper condition first.

trx_purge(): Atomically access purge_sys.n_completed.
Remove some code duplication.

trx_purge_wait_for_workers_to_complete(): Atomically access
purge_sys.n_completed. Remove an unnecessary local variable.

trx_purge_stop(): Remove a redundant assignment.

row_ins_sec_index_entry(): Compare a pointer to fil_system.sys_space,
not to a numeric constant. This code was recently changed in MDEV-13637,
and the condition was essentially disabled, potentially causing the
change buffer to grow uncontrollably when something is inserted into
a table that has secondary indexes and resides in the system tablespace.

Thanks to Daniel Black for pointing out that clang 7 flagged a warning
for the comparison of a pointer to an integer.

row_import_for_mysql(): Fix a possible compiler warning.

There is no need for MariaDB Backup to be versioned. Other packages are
very unlikely to need to depend on a certain generation of this package.

Also for MariaDB Backup to run, it does not need the server, but client,
and from client only core parts.

dict_sys_tables_type_valid(): Do not reject NO_ROLLBACK (sequence)
in ROW_FORMAT=REDUNDANT.

dict_load_table_low(): When flagging an error, assign *table = NULL.
Failure to do so could cause a crash if an error was flagged when
accessing INFORMATION_SCHEMA.INNODB_SYS_TABLES.

make its lifetime as short as possible

for historical row ROW_COPY_DATA -> ROW_COPY_POINTER for lower memory
consumption and better performance

MDEV-15742 Assertion `table_share->tmp_table != NO_TMP_TABLE ||
m_lock_type == 1' failed in handler::ha_write_row

Renaming methods:
- Field::make_field(Send_field*) to make_send_field(..)
- Item::make_field(THD *,Send_field *) to make_send_field(..)
- Item::init_make_field(Send_field *, enum_field_type) to init_make_send_field(..)

These names looked similar to other functions that are used
for a very different purpose (creating Field instances):
- Public function "Field * make_field(..)"
- Method "Field *Column_defitinion::make_field(..)"

The rename makes it's easier to search the code using "grep".

MDEV-14762 Server crashes in MDL_ticket::has_stronger_or_equal_type upon inserting into temporary sequence

Fix is to not upgrade MDL locks for temporary tables

Found via `codespell -i 3 -w --skip="./debian/po" -I ../mariadb-server-word-whitelist.txt  ./cmake/ ./debian/ ./Docs/ ./include/ ./man/ ./plugin/ ./strings/`

Problem was the Item_field::Item_field(THD*, Field*) had old code
that put a null pointer in orig_field_names. Now, when we have
proper re-prepare if table definition changes, this is not needed
anymore.