thanks @FaramosCZ

Even if Makefile for some reason was checked in in a submodule,
it is still a generated file, will be cleaned, won't be in a source
package. One cannot jump to conclusions if it doesn't exist.

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.

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.

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.

For some reason, GCC 8 did not issue warnings for all such comparisons.

row_is_mysql_tmp_table_name(): Replaced with
dict_table_t::is_temporary_name() and table_name_t::is_temporary().

table_name_t: Add constructors.

In MariaDB, InnoDB tables will always contain DATA_N_SYS_COLS = 3
columns, 2 or 3 of which are present in the clustered index.
We remove the predicate that was added in MySQL 5.7 as part of WL#7682.

InnoDB and XtraDB had redundant assertions for checking that
function parameters that were declared as nonnull were not NULL.

it was supposed to be `*(p-1)` not `*p-1`
(the crash happens if `*p==0`)

in particular, don't search for libjemalloc.a, which is only
needed for tokudb's ftcxx tests, when the tests aren't going
to be built.

`zypper install krb5-devel` installs executables outside of $PATH.
It also installs /etc/profile.d/krb5.sh that is sourced by a new
shell to add the new location to the $PATH. But this doesn't affect
the current shell.

Now decent Linux distros remind the user to run `. /etc/profile`
to reload paths in such a case. SUSE doesn't and for a good reason -
it doesn't work there. Because SUSE sets PROFILEREAD=true in the
environment and /etc/profile does not do anything.

By this point, one should not really expect `unset PROFILEREAD` to help,
and it does not - PROFILEREAD is readonly, and cannot be unset.

Apparently SUSE really *really* wants you to re-login between installing
MariaDB build dependencies and actually running the rpmbuild.

Which we cannot do it buildbot. And it would look very user-un-friendly
in the Build Instructions section of the manual.

So, we work around it - by adding SUSE krb5 path to the search list.

THIS IS SUSEEEEEE!!!

Filter out most common file types from automatic dependency collection.
This makes `make package`  in centos73 VM three times faster

MariaDB does support InnoDB tables with no stored columns.
(They are necessarily empty.)

On Microsoft Windows, InnoDB writes the path separator \ to the
redo log file, while on all other platforms, / is being used.

fil_name_parse(): Normalize the parsed path separators to the
native format. This allows backups or data sets to be portable
between Windows and other systems.

This is follow-up for commit 619d22dd
to fix the cmake -DWITH_EMBEDDED_SERVER build.