- Remove unused variables
- Mark variables unused
- Fix wrong types
- Add no-strict-aliasing to BUILD scripts

Allow to exclude certain databases from an --all-databases dump,
e.g. to be able to do

  mysqldump --all-databases --ignore-database=mysql

to dump everything but the system tables.

When skipping the MDEV-11369 'default row' record, check again
for an empty page.

The rollback of the modification of a pre-existing record
should involve a purge-like operation. Before MDEV-12288
the only purge-like operation was the removal of a
delete-marked record.

After MDEV-12288, any rollback of updating an existing record
must reset the DB_TRX_ID column when it is no longer visible
in the purge read view.

row_vers_must_preserve_del_marked(): Remove. It is cleaner to
perform the check directly in row0umod.cc.

row_trx_id_offset(): Auxiliary function to retrieve the byte
offset of DB_TRX_ID in a clustered index leaf page record.

row_undo_mod_must_purge(): Determine if a record should be purged.

row_undo_mod_clust(): For temporary tables, skip the purge checks.
When rolling back an update so that the original record was not
delete-marked, reset DB_TRX_ID if the history is no longer visible.

Recent changes in semisync initialization via MDEV-13073 introduced
instantiation of THD too early from the server components
pov which led to segfault.

Fixed with relocating the semisync component initialization
to later time when thread specific memory can be used.

Fixed typo on select that is executed only when something unexpected
happens.

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

Use block->page.offset for checking page number.

Problem was that we did not delete explain information
when Galera must replay a query.

Could not find easily repeatable test case that would not
cause other problems.

followup for 339b9055

don't use $opt_gdb for --client-gdb

mark CONNECTION_ID() as returning *unsigned* number

fix versioning.partition failures:
* Make the test stable by setting timestamp to fixed values.

The error occurs because of how the character set and collation are chosen for
stored procedure parameters that have a character data type.  If the character
set and collation are not explicitly stated in the declaration, the server
chooses the database character set and collation in effect at routine creation
time.

To fix the problem, I added explicit character set and collation attributes
for the stored procedure parameters in the install_spider.sql script.

Author:
  Jacob Mathew.

Reviewer:
  Kentoku Shiba.

Merged From:
  bb-10.3-MDEV-15692

It was on for alpha stages of 10.3, and now we're past that.

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.

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.

If we use hostnames, it will fail during name resolution on UNIX systems

Also fix perfschema.hostcache_ipv6_max_con.
The test case makes use of a debug switch to execute some special code.
The code does hostname replacement. Every hostname sent during connect
phase becomes santa.claus.ipv4.example.com (or ipv6). This causes a
connection from root@localhost to fail, as root is not registered as
santa claus user. The failure is only apparent on Windows as Unix
systems make use of sockets, which bypass the name resolution check
entirely.

Fix 10.2-specific bug - copy-back is not prepared to handle system
tablespaces with absolute path.

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.

The implementations of the convert_to_basic_const_item() virtual
function for the Item_cache classes should call cache_value() when
value_cached == NULL.

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

There was a missing argument to service_manager_extend_timeout call
and the signness of arguments did not match.

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