Two new information_schema views are added:
* PERIOD table -- columns TABLE_CATALOG, TABLE_SCHEMA, TABLE_NAME,
  PERIOD_NAME, START_COLUMN_NAME, END_COLUMN_NAME.
* KEY_PERIOD_USAGE -- works similar to KEY_COLUMN_USAGE, but for periods.
  Columns CONSTRAINT_CATALOG, CONSTRAINT_SCHEMA, CONSTRAINT_NAME,
  TABLE_CATALOG, TABLE_SCHEMA, TABLE_NAME, PERIOD_NAME

Two new columns are added to the COLUMNS view:
 IS_SYSTEM_TIME_PERIOD_START, IS_SYSTEM_TIME_PERIOD_END - contain YES/NO.

Embedded server has an option to opt out grant checks.
sql_show.cc: reduce ifdefs by using embedded acl stub calls
sql_acl.cc: add stub for embedded get_column_grant

Adjust test after fixing the C/C.

On Windows, use --host=127.0.0.2 to fake "insecure" transport
with TCP connection for test purposes. 127.0.0.2 is loopback address,
that can be used instead of usual 127.0.0.1

Unfortunately, this technique does not work on all *nixes the same,
notably neither on BSDs nor Solaris. Thus default --host=localhost
remains "insecure" transport,when TCP is used. but it is not that critical,
the "self-signed" is not nearly as annoying on *nixes as it is on Windows.

Changing the format in error messages:
- ER_PACKAGE_ROUTINE_IN_SPEC_NOT_DEFINED_IN_BODY
- ER_PACKAGE_ROUTINE_FORWARD_DECLARATION_NOT_DEFINED

from
  "Subroutine 'db.pkg.f1' ..."

to a more clear:
  "FUNCTION `db.pkg.f1` ..."
  "PROCEDURE `db.pkg.p1` ..."

This reverts commit c37b2087.

In c37b20887, when re-binlogging a GTID event on a replica,
it will overwrite the thread_id from the primary to be the
value of the slave applier (SQL thread or parallel worker).

This should be the value of the original thread_id on the
master connection though, to both help track temporary
tables, and be consistent with Query_log_event.

Reverting the commit to re-target 11.5, so we can re-test
with the corrected thread_id.

When displaying the ER_SP_DOES_NOT_EXIST error, use
Sp_handler::type_lex_cstring() to the the underlying
object type:
- PROCEDURE
- FUNCTION
- PACKAGE
- PACKAGE BODY
instead of hard-coded "FUNCTION or PROCEDURE".

* --ssl-verify-server-cert was not enabled explicitly, and
* CA was not specified, and
* fingerprint was not specified, and
* protocol is TCP, and
* no password was provided

insecure passwordless logins are common in test environment, let's
not break them. practically, it hardly makes sense to have strong
MitM protection if an attacker can simply login without a password.

Covers mariadb, mariadb-admin, mariadb-binlog, mariadb-dump

enable ssl + ssl_verify_server_cert in the internal client too

* fix replication tests to disable master_ssl_verify_server_cert
  because accounts are passwordless - except rpl.rpl_ssl1
* fix federated/federatedx/connect to disable SSL_VERIFY_SERVER_CERT
  because they cannot configure an ssl connection
* fix spider to disable ssl_verify_server_cert, if configuration
  says so, as spider _can_ configure an ssl connection
* memory leak in embedded test-connect

port the client-side implementation from C/C to the internal client.
add the test.

because it doesn't work. CONC-635.

it's not an ssl option, so shouldn't be in mysql_ssl_free(),
which frees ssl options, and only unless CLIENT_REMEMBER_OPTIONS is set.

mysql->connector_fd must be freed when mysql->net.vio is closed
and fd becomes no longer valid

use SSL_VERIFY_PEER with the "always ok" callback,
instead of SSL_VERIFY_NONE with no callback.

The latter doesn't work correctly in wolfSSL, it accepts self-signed
certificates just fine (as in OpenSSL), but after that
SSL_get_verify_result() returns X509_V_OK, while it returns an error
(e.g. X509_V_ERR_SELF_SIGNED_CERT_IN_CHAIN) in OpenSSL.

X509_check_host() and X509_check_ip_asc() exist in all
supported SSL libraries

in OpenSSL >= 1.0.2 and in the bundled WolfSSL

And X509_free() handles NULL pointers all right.

* type of mi->ssl_verify_server_cert must be my_bool, because it's
  passed by address to mysql_options(), and the latter expects my_bool
* explicitly disable ssl in MYSQL if mi->ssl is 0
* remove dead code (`#ifdef NOT_USED`)
* remove useless casts and checks replacing empty strings with NULL
  (new_VioSSLFd() does that internally)

except in bootstrap

if the server is started with --ssl but without neither --ssl-key nor
--ssl-cert, let it automatically generate a self-signed certificate.
It's generated in memory only and never saved to disk.

when neither --ssl-key nor --ssl-cert were set, the errror
was "Private key does not match the certificate public key"

changed to "Unable to get certificate"

verify that --ssl-verify-server-cert detects cert mismatch,
but with --disable-ssl-verify-server-cert the connection succeeds

implement --ssl-fp and --ssl-fplist for all clients.
--ssl-fp takes one certificate fingerprint, for example,
00:11:22:33:44:55:66:77:88:99:AA:BB:CC:DD:EE:FF:00:11:22:33

--ssl-fplist takes a path to a file with one fingerprint per line.

if the server's certificate fingerprint matches ssl-fp or is found
in the file - the certificate is considered verified.
If the fingerprint is specified but doesn't match - the connection
is aborted independently from the --ssl-verify-server-cert

if the client enabled --ssl-verify-server-cert, then
the server certificate is verified as follows:

* if --ssl-ca or --ssl-capath were specified, the cert must have
  a proper signature by the specified CA (or CA in the path)
  and the cert's hostname must match the server's hostname.
  If the cert isn't signed or a hostname is wrong - the
  connection is aborted.

* if MARIADB_OPT_TLS_PEER_FP was used and the fingerprint matches,
  the connection is allowed, if it doesn't match - aborted.

* If the connection uses unix socket or named pipes - it's allowed.
  (consistent with server's --require-secure-transport behavior)

otherwise the cert is still in doubt, we don't know if we can trust
it or there's an active MitM in progress.

* If the user has provided no password or the server requested an
  authentication plugin that sends the password in cleartext -
  the connection is aborted.

* Perform the authentication. If the server accepts the password,
  it'll send SHA2(scramble || password hash || cert fingerprint)
  with the OK packet.

* Verify the SHA2 digest, if it matches - the connection is allowed,
  otherwise it's aborted.

char is a character, uchar is an octet.
casts removed (or added) as needed

not default_mysqld.cnf. The latter has only server settings,
it misses mtr-specific client configuration

Except for spider, that doesn't use mysqld.1 server
and default_my.cnf starts it automatically.
Spider tests have to include both default_mysqld.cnf and
default_client.cnf

it's for client auth plugins only, server auth plugin should never
return it, because they cannot send a correct OK packet.
(OK packet is quite complex and carries a lot of information that
only the server knows)

as suggested by Monty

This commit addresses multiple server shutdown problems observed on macOS,
Solaris, and FreeBSD:

1. Corrected a non-portable assumption where socket shutdown was expected
to wake up poll() with listening sockets in the main thread.

Use more robust self-pipe to wake up poll() by writing to the pipe's write
end.

2. Fixed a random crash on macOS from pthread_kill(signal_handler)
when the signal_handler was detached and the thread had already exited.

Use more robust `kill(getpid(), SIGTERM)` to wake up the signal handler
thread.

3. Made sure, that signal handler thread always exits once `abort_loop` is
set, and also calls `my_thread_end()` and clears `signal_thread_in_use`
when exiting.

This fixes warning "1 thread did not exit"  by `my_global_thread_end()`
seen on FreeBSD/macOS when the process is terminated via signal.

Additionally, the shutdown code underwent light refactoring
for better readability and maintainability:
- Modified `break_connect_loop()` to no longer wait for the main thread,
  aligning behavior with Windows (since 10.4).
- Removed dead code related to the unused `USE_ONE_SIGNAL_HAND`
  preprocessor constant.
- Eliminated support for `#ifndef HAVE_POLL` in `handle_connection_sockets`
  This code is also dead, since 10.4

This is done for symmetry with mariadb-dump, which does not use threads
but allows parallelism via --parallel

Traditional --use-threads can still be used, it is synonymous
with --parallel

-  --parallel=N with or without --single-transaction
-  Error cases (too many connections, emulate error on one connection)
-  Windows specific test for named pipe connections

At the moment, it only works with --tab, to execute "SELECT INTO OUTFILE"
queries concurrently.

Uses connection_pool for concurrent execution.

Parallelism is achieved by using mysql_send_query on multiple connections
without waiting for results, and using IO multiplexing (poll/IOCP) to
wait for completions.

Refresh libmariadb to pick up CONC-676 (fixes for IOCP use with named pipe)