On Linux, <fcntl.h> declares open(2) as having a nonnull first argument.
In GCC 8, if a function with nonnull argument is called, that argument
will be silently assumed to nonnull along the same code path. Hence,
later nullness checks for this argument can be optimized away.

Similar to MDEV-15587, the fix is to ensure that functions with
nonnull arguments are not being called with NULL.

This bug caused a crash in mysqlbinlog, which was invoking
create_temp_file() with the argument dir=NULL. The affected test was
binlog.binlog_mysqlbinlog_base64. It would display the following message
before crashing:

mysqlbinlog: O_TMPFILE is not supported on (null) (disabling future attempts)
Segmentation fault

This is a follow-up to MDEV-18733. As part of that fix, we made
dict_check_sys_tables() skip tables that would be dropped by
row_mysql_drop_garbage_tables().

DICT_ERR_IGNORE_DROP: A new mode where the file should not be attempted
to be opened.

dict_load_tablespace(): Do not try to load the tablespace if
DICT_ERR_IGNORE_DROP has been specified.

row_mysql_drop_garbage_tables(): Pass the DICT_ERR_IGNORE_DROP mode.

fil_space_for_table_exists_in_mem(): Remove a parameter.
The only caller that passed print_error_if_does_not_exist=true
was row_drop_single_table_tablespace().

The recv_sys data structures are accessed not only from the thread
that executes InnoDB plugin initialization, but also from the
InnoDB I/O threads, which can invoke recv_recover_page().

Assert that sufficient concurrency control is in place.
Some code was accessing recv_sys data structures without
holding recv_sys->mutex.

recv_recover_page(bpage): Refactor the call from buf_page_io_complete()
into a separate function that performs necessary steps. The
main thread was unnecessarily releasing and reacquiring recv_sys->mutex.

recv_recover_page(block,mtr,recv_addr): Pass more parameters from
the caller. Avoid redundant lookups and computations. Eliminate some
redundant variables.

recv_get_fil_addr_struct(): Assert that recv_sys->mutex is being held.
That was not always the case!

recv_scan_log_recs(): Acquire recv_sys->mutex for the whole duration
of the function. (While we are scanning and buffering redo log records,
no pages can be read in.)

recv_read_in_area(): Properly protect access with recv_sys->mutex.

recv_apply_hashed_log_recs(): Check recv_addr->state only once,
and continuously hold recv_sys->mutex. The mutex will be released
and reacquired inside recv_recover_page() and recv_read_in_area(),
allowing concurrent processing by buf_page_io_complete() in I/O threads.

The record MLOG_INDEX_LOAD is supposed to be written to indicate that
some page modifications bypassed redo logging, and that redo logging
is now re-enabled. It was not written for fulltext indexes during
ALTER TABLE.

row_merge_write_redo(): Declare globally. Assert that the index
is neither a spatial nor fulltext index.

recv_mlog_index_load(): Observe a MLOG_INDEX_LOAD operation.

recv_parse_log_recs(): Handle MLOG_INDEX_LOAD also in multi-record
mini-transactions. Because of this omission, we should keep writing
MLOG_INDEX_LOAD in single-record mini-transactions, because older
versions of Mariabackup would fail.

row_fts_merge_insert(): Write MLOG_INDEX_LOAD for the auxiliary
tables of fulltext indexes.

The record MLOG_ZIP_PAGE_COMPRESS is similar to MLOG_INIT_FILE_PAGE2
that it contains all the information needed to initialize the page.
Like for the other record, do initialize the entire page on recovery.

The page_size argument to buf_page_get_gen() only matters when the
page is going to be loaded into the buffer pool. Allow callers to
pass a dummy parameter when using BUF_GET_IF_IN_POOL (which would
return NULL if the block is not in the buffer pool).

btr_root_get(): Ignore the root->page.encrypted flag.
The purpose of this flag is questionable since
commit 8c43f963.

btr_validate_index(): Avoid crash if btr_root_get() returns NULL.

btr_free_root(): Add the parameter bool invalidate.

btr_free_root_invalidate(): Remove.

fsp_apply_init_file_page(): Renamed from fsp_init_file_page_low().

fsp_parse_init_file_page(): Remove. The redo log record has no
parameters.

Normally, InnoDB is not in the process of executing crash recovery.
Provide a hint to the compiler that the recovery-related code paths
are rarely executed.

- Changed replaying to always allocate a separate THD object
  for applying log events. This is to avoid tampering original
  THD state during replay process.
- Return success from sp_instr_stmt::exec_core() if replaying
  succeeds.
- Do not push warnings/errors into diagnostics area if the
  transaction must be replayed. This is to avoid reporting
  transient errors to the client.

Added two tests galera_sp_bf_abort, galera_sp_insert_parallel.
Wsrep-lib position updated.

	deleted:    mysql-test/suite/galera/r/MW-86.result
	deleted:    mysql-test/suite/galera/r/mysql-wsrep#216.result
	modified:   mysql-test/suite/galera/t/GCF-1081.test
	modified:   mysql-test/suite/galera_3nodes_sr/r/GCF-832.result
	modified:   mysql-test/suite/galera_3nodes_sr/t/GCF-810A.test
	modified:   mysql-test/suite/galera_3nodes_sr/t/GCF-810B.test
	modified:   mysql-test/suite/galera_3nodes_sr/t/GCF-810C.test
	modified:   mysql-test/suite/galera_3nodes_sr/t/GCF-832.test
	modified:   mysql-test/suite/galera_sr/r/mysql-wsrep-features#35.result
	modified:   mysql-test/suite/galera_sr/t/mysql-wsrep-features#35.test

If SUBS_IN_TO_EXISTS strategy has been chosen for a subquery then
additional conditions are injected into WHERE/ON/HAVING of this subquery
and it may happen that test_quick_select() invoked from
JOIN::make_range_rowid_filters() discovers impossible range. This
must be checked.

With INFORMATION_SCHEMA set as the default database the check that a table
referred in the processed query is defined in INORMATION_SCHEMA must
be postponed until all CTE names can be identified.

Temporary table is defined with the view field in HAVING.
Item_direct_view_ref for this field is dropped and that causes error.

To fix it Item_direct_view_ref::remove_item_direct_ref() is added.

The bug occurs because of the wrong pushdown of constant function
defined with subquery from HAVING into WHERE. Subqueries can't be
pushed into WHERE.

To fix it with_subquery() call is added to check if the function contains
subquery.

A syntax error was reported for any INSERT statement with explicit
partition selection it if i used a column list.
Fixed by saving the parsing place before parsing the clause for explicit
partition selection and restoring it when the clause has been parsed.

    This bug is caused by pushdown from HAVING into WHERE.
    It appears because condition that is pushed wasn't fixed.

    It is also discovered that condition pushdown from HAVING into
    WHERE is done wrong. There is no need to build clones for some
    conditions that can be pushed. They can be simply moved from HAVING
    into WHERE without cloning.
    build_pushable_cond_for_having_pushdown(),
    remove_pushed_top_conjuncts_for_having() methods are changed.

    It is found that there is no transformation made for fields of
    pushed condition.
    field_transformer_for_having_pushdown transformer is added.

    New tests are added. Some comments are changed.

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.

Normally, InnoDB will create temporary table names of the form
#sql-ibNNNN, and with innodb_safe_truncate=OFF, #sql-ibNNNN-MMMM.

If InnoDB crash recovery was needed, the InnoDB function srv_start()
would invoke extra validation, reading something from every InnoDB
data file. This should be unnecessary now that MDEV-14717 made
RENAME operations crash-safe inside InnoDB (which can be
disabled in MariaDB 10.2 by setting innodb_safe_truncate=OFF).

dict_check_sys_tables(): Skip tables that would be dropped by
row_mysql_drop_garbage_tables(). Perform extra validation only
if innodb_safe_truncate=OFF, innodb_force_recovery=0 and
crash recovery was needed.

dict_load_table_one(): Validate the root page of the table.
In this way, we can deny access to corrupted or mismatching tables
not only after crash recovery, but also after a clean shutdown.

Just rename index in data dictionary and in InnoDB cache when it's possible.
Introduce ALTER_INDEX_RENAME for that purpose so that engines can optimize
such operation.

Unused code between macro MYSQL_RENAME_INDEX was removed.

compare_keys_but_name(): compare index definitions except for index names

Alter_inplace_info::rename_keys:
ha_innobase_inplace_ctx::rename_keys: vector of rename indexes

fill_alter_inplace_info():: fills Alter_inplace_info::rename_keys