buf_page_get_low(): If the page was read-fixed, validate the page ID
because the page could have been marked as corrupted. We should retry
the page read in this case, instead of returning a soon-to-be-evicted
corrupted page to the caller.

This was initially only observed on Microsoft Windows.
On Linux, this was repeated after adding a sleep
to buf_pool_t::corrupted_evict() between
bpage->zip.fix.fetch_sub() and bpage->lock.x_unlock().

In commit 9bc874a5 (MDEV-23497)
the configuration option innodb_read_only_compressed was introduced
to giver users advance notice of a plan to remove ROW_FORMAT=COMPRESSED
support for InnoDB.

Based on user feedback, this plan has been scrapped.
Even though ROW_FORMAT=COMPRESSED is a dead end and causes some
overhead for InnoDB data structures, we can live with that.

Now that we know that some users really want to keep using
ROW_FORMAT=COMPRESSED, the previous default value of the parameter
innodb_read_only_compressed=ON should be changed to OFF, to allow
smooth upgrades to 10.6 and later versions, without requiring users
to update any configuration file.

- Store the deferred tablespace name while loading the tablespace
for backup process.

- Mariabackup stores the list of space ids which has page0 INIT_PAGE
records. backup_first_page_op() and first_page_init() was introduced
to track the page0 INIT_PAGE records.

- backup_file_op() and log_file_op() was changed to handle
FILE_MODIFY redo log records. It is used to identify the
deferred tablespace space id.

- Whenever file operation redo log was processed by backup,
backup_file_op() should check whether the space name exist
in deferred tablespace. If it is then it needs to store the
space id, name when FILE_MODIFY, FILE_RENAME redo log processed
and it should delete the tablespace name from defer list in other
cases.

- backup_fix_ddl() should check whether deferred tablespace has
any page0 init records. If it is then consider the tablespace
as newly created tablespace. If not then backup should try
to reload the tablespace with SRV_BACKUP_NO_DEFER mode to
avoid the deferring of tablespace.

Make installer fail if INSTALLDIR exists.
In UI mode, show a popup and disable "Next" button until install root is
corrected

This happens for example if one installs into home directory of a user
C:\Users\<username>\mariadb

The reason is that the service user "NT SERVICE\<service_name>" does
not have read and execute permissions for service executable mysqld.exe
in this directory.
Moreover, it would not have read permissions for server.dll loaded by the
exe, or to plugin directory, where plugins may reside.

The fix is to give service users read and execute permissions to bin, share, and
lib\plugin subdirectories.

The permission setting is doneby  mysql_install_db.exe, but also in MSI.
It is important to do that in MSI, as we want permissions to survive
the MSI upgrade.

fixes errors on rpm-*-debug builder

when it's run directly after main.mysql_json_mysql_upgrade

because mysqld--help-aria starts a second mysqld that reads the plugin
table, so it has to be flushed and closed at that time.

fixes errors on rpm-*-debug builder

this fixes plugins.qc_info in --embed

followup for 430d60d1 MDEV-24487

Add error from later versions to avoid chaging HA_ERR_*
accross versions and in already released versions.

this fixes main.partition_cache and main.cache_innodb in --embed

followup for 430d60d1 MDEV-24487

pass the pointer to thd->killed down to the json library,
check it while scanning,
use thd->check_killed() to generate the proper error message

preallocate the string in json_nice()
to avoid reallocs on every 1-character append()

that was permanently disabled in a merge mistake. also
* use auth_test_plugin to test dumping of plugins and user auth,
  as the original test intended
* s/USER/foobar/ to make a username searchable

revert 68b3fa88

accessing freed memory.
Before XMLCOL::WriteColumn() Tdbp->Clist gets assigned
a nodelist in

      Clist = RowNode->SelectNodes(g, Colname, Clist);

which is RowNode->Doc->Xop->nodesetval.

In XMLCOL::WriteColumn()

        ValNode = ColNode->SelectSingleNode(g, Xname, Vxnp);

calls LIBXMLDOC::GetNodeList() again, which frees the previous
XPath object Xop and replaces it with a new one.

In this case RowNode->Doc == ColNode->Doc, so Clist->Listp
points to a freed memory now.

fix it for Aria too

MDEV-27668 Assertion `item->type_handler()->is_traditional_scalar_type() || item->type_handler() == type_handler()' failed in Field_inet6::can_optimize_keypart_ref

The correct macro to detect the AMD64 ISA is _M_X64, not M_IX64.

This is the 10.6 version of
commit fb8fea34 (10.5).

- Revert wrongly record embedded result files. These were either
  recorded with normal server (not embedded) or an embedded server
  with not default compile option. This can be seen that the committed
  result file had replication variables which should never happen.

- Reverted back change of include/is_embedded.inc. One cannot check for
  $MYSQL_EMBEDDED as this only tells if there exists an embedded
  server, not if the current server we are testing is the embedded
  server. This could easily be verified by doing
  'mtr sys_vars.sysvars_server_embedded'. This would fail with a wrong
  result instead of being marked as skipped as --embedded was not
  used.

This happens when compiled with HAVE_EMBEDDED_PRIVILEGE_CONTROL.
There is a lot of other problems with the above option that should
be fixed at some point

The correct macro to detect the AMD64 ISA is _M_X64, not M_IX64.

Thanks to Vladislav Vaintroub for pointing this out.

Even though Apple Xcode is based on and similar to Clang,
it does not support the asm goto construct which was added
in commit 668a5f3d (MDEV-26720)
to work around a compiler deficiency that results in suboptimal
code being generated for IA-32 and AMD64.

We will disable this manual optimization if __APPLE_CC__ is defined.

Similar constructs are also used in sync/srw_lock.cc, but that code
is not used on Apple, because we have not implemented a Linux futex
compatible interface on Apple macOS.

Thanks to Valerii Kravchuk for reporting and testing this.