this partially reverts 6e56ebbb498

* update cracklib_password_check to match the new prototype
* cannot use __attribute__((format)) for my_snprintf, because
  we support format extensions that the compiler doesn't know about.

- Added sql/mariadb.h file that should be included first by files in sql
  directory, if sql_plugin.h is not used (sql_plugin.h adds SHOW variables
  that must be done before my_global.h is included)
- Removed a lot of include my_global.h from include files
- Removed include's of some files that my_global.h automatically includes
- Removed duplicated include's of my_sys.h
- Replaced include my_config.h with my_global.h

- Use microsecond_interval_timer() to calculate time for applying row events.
  (Faster execution)
- Removed return value for set_row_stmt_start_timestamp()
  as it was never used.

Don't use the server's version, that expects a valid THD.
Modify net_serv.cc not not use any THD if MYSQL_SERVER isn't defined.

This reverts commit aaddac5c.

accept proxy protocol header from client connections.
The new server variable 'proxy_protocol_networks' contains list
of networks from which proxy header is accepted.

platform independent.

It allows to push conditions into derived with window functions not
only in the cases when the window specifications of these window
functions use the same partition, but also in the cases when the window
functions use partitions that share only some fields. In these
cases only the conditions over the common fields are pushed.

With MDEV-12288 and MDEV-13536, the InnoDB purge threads will access
pages more often, causing all sorts of debug assertion failures in
the B-tree code.

Work around this problem by amending the corruption tests with
--innodb-purge-rseg-truncate-frequency=1 --skip-innodb-fast-shutdown
so that everything will be purged before the server
is restarted to deal with the corruption.

This should have been part of MDEV-12288.

trx_undo_t::del_marks: Remove.
Purge needs to process all undo log records in order to
reset the DB_TRX_ID. Before MDEV-12288, it sufficed to only delete
the purgeable delete-marked records, and it ignore other undo log.

trx_rseg_t::needs_purge: Renamed from trx_rseg_t::last_del_marks.
Indicates whether a rollback segment needs to be processed by purge.

TRX_UNDO_NEEDS_PURGE: Renamed from TRX_UNDO_DEL_MARKS.
Indicates whether a rollback segment needs to be processed by purge.
This will be 1 until trx_purge_free_segment() has been invoked.

row_purge_record_func(): Set the is_insert flag for TRX_UNDO_INSERT_REC,
so that the DB_ROLL_PTR will match in row_purge_reset_trx_id().

trx_purge_fetch_next_rec(): Add a comment about row_purge_record_func()
going to set the is_insert flag.

trx_purge_read_undo_rec(): Always attempt to read the undo log record.

trx_purge_get_next_rec(): Do not skip any undo log records.
Even when no clustered index record is going to be removed,
we may want to reset some DB_TRX_ID,DB_ROLL_PTR.

trx_undo_rec_get_cmpl_info(), trx_undo_rec_get_extern_storage(): Remove.

trx_purge_add_undo_to_history(): Set the TRX_UNDO_NEEDS_PURGE flag
so that the resetting will work on undo logs that were originally
created before MDEV-12288 (MariaDB 10.3.1).

trx_undo_roll_ptr_is_insert(), trx_purge_free_segment(): Cleanup
(should be no functional change).

Recording more tests for MDEV-13500 sql_mode=ORACLE: can't create a virtual column with function MOD

Some affected tests require --big-test.
They were forgotten in the main patch.

Corrected an assertion in the constructor for the class Sys_var_flagset.