The previous commit was erroneously marked as MDEV-23162.
The correct issue is MDEV-23478.

An alternative implementation (replacing the one based on repertoire).

This implementation makes Field send itself to Protocol_text using
data type specific Protocol methods rather than field->val_str()
followed by protocol_text->store_str().

As now Field sends itself in the same way to all protocol types
(e.g. Protocol_binary, Protocol_text, Protocol_local),
the method Field::send_binary() was renamed just to Field::send().

Note, this change introduces symmetry between Field and Item,
because Items also send themself using a single method Item::send(),
which is used for *all* protocol types.

Performance improvement is achieved by the fact that Protocol_text
implements these data type specific methods using store_numeric_string_aux()
rather than store_string_aux(). The conversion now happens only when
character_set_results is not ASCII compatible character sets
(e.g. UCS2, UTF16, UTF32).

In the old code (before any MDEV-23162 work, e.g. as of 10.5.4),
Protocol_text::store(Field*) used val_str() for all data types.
So the execution went through the character set conversion routines
even for numeric and temporal data types.

Benchmarking summary (see  details in MDEV-23478):

The new approach stably demonstrates additional improvement comparing
to the previous implementation (the smaller time - the better):

Original   - the commit before MDEV-23162
             be98036f

        1m9.336s
        1m9.290s
        1m9.300s

MDEV-23162 - the repertoire optimization

        1m6.101s
        1m5.988s
        1m6.264s

MDEV-23478 - this commit

        1m2.150s
        1m2.079s
        1m2.099s

This reverts commit eb2eaba7.

A different implementation of MDEV-23162 is coming.

As the first entry, define user 'ottok' (Otto Kekäläinen) as the person
who by default gets assigned all PRs that modify the debian/ contents.

There is no mysql_upgrade_wizard target, only mariadb-upgrade-wizard

The post-build custom command to embed Vista elevation manifest into
mariadb-upgrade-wizard.exe seems to do
something nasty to the executable, perhaps it removes and recreates it.

Thus the previously created hardlink mysql_upgrade_wizard is not marked
to require elevation.

Solved by using MANIFESTUAC linker flag, rather than invoke mt.exe.
This avoids an extra post-build step that modifies mariadb-upgrade-wizard.exe

IFNULL(inet6_not_null_expr, 'foo') erroneously set its nullability to NOT NULL.

Fix:
- Moving the line "maybe_null= args[1]->maybe_null" before the call
  of fix_length_and_dec2(), so the call of Type_handler method
  Item_hybrid_func_fix_attributes() can reset it when desired.

- Fixing Type_handler_inet6::Item_hybrid_func_fix_attributes()
  to ignore args[0] when detecting nullability of IFNULL().

In the merge eae968f6, it turns out that
I had accidentally initiated an in-source build in the past, and
$MYSQL_TZINFO_TO_SQL was pointing to a stale copy of the executable in
the source directory, instead of the correct one in the build directory.

The test timeouts, because mtr is waiting for pid file.
The pid file is not there, because expected to fail mysqld startup
(duplicate named pipe name), this startup removed pid file of the running
mysqld instance.

To fix, split handle_connections_win() into the initialization part,
and  accept/handle part, like it is done elsewhere.

The initialization part runs before pid file handling, and aborts on errors
, thus avoiding pid file overwrites.

The test encryption.create_or_replace would occasionally fail,
because some fil_space_t::n_pending_ops would never be decremented.

fil_crypt_find_space_to_rotate(): If rotate_thread_t::should_shutdown()
holds due to innodb_encryption_threads having been reduced, do
release the reference.

fil_space_remove_from_keyrotation(), fil_space_next(): Declare the
functions static, simplify a little, and define in the same compilation
unit with the only caller, fil_crypt_find_space_to_rotate().

fil_crypt_key_mutex: Remove (unused).

The background DROP TABLE queue may be blocked for some more time
due to MDEV-16678. Let us apply similar adjustments as earlier:
commit 6af00b2c
commit 89633995
commit ccd87d34

Example of the failure:
http://buildbot.askmonty.org/buildbot/builders/bld-p9-rhel7/builds/4417/steps/mtr/logs/stdio
```
main.mysqld--help 'unix'                 w17 [ fail ]
        Test ended at 2020-06-20 18:51:45

CURRENT_TEST: main.mysqld--help
--- /opt/buildbot-slave/bld-p9-rhel7/build/mysql-test/main/mysqld--help.result	2020-06-20 16:06:49.903604179 +0300
+++ /opt/buildbot-slave/bld-p9-rhel7/build/mysql-test/main/mysqld--help.reject	2020-06-20 18:51:44.886766820 +0300
@@ -1797,10 +1797,10 @@
 sync-relay-log-info 10000
 sysdate-is-now FALSE
 system-versioning-alter-history ERROR
-table-cache 421
+table-cache 2000
 table-definition-cache 400
-table-open-cache 421
-table-open-cache-instances 1
+table-open-cache 2000
+table-open-cache-instances 8
 tc-heuristic-recover OFF
 tcp-keepalive-interval 0
 tcp-keepalive-probes 0

mysqltest: Result length mismatch
```
mtr: table_open_cache_basic autosized:

Lets assume that >400 are available and that
we can set the result back to the start value.

All of these system variables are autosized and can
generate MTR output differences.

Closes #1527

MDEV-23415 Server crash or Assertion `dec_length <= str_length' failed in Item_func_format::val_str_ascii

Problem:

The crash happened in FORMAT(double, dec>=31, 'de_DE').

The patch for MDEV-23118 (commit 0041dacc)
did not take into account that String::set_real() has a limit of 31
(FLOATING_POINT_DECIMALS) fractional digits. So for the range of 31..38
digits, set_real() switches to use:
- my_fcvt() - decimal point notation, e.g. 1.9999999999
- my_gcvt() - scientific notation,    e.g. 1e22

my_gcvt() returned a shorter string than Item_func_format::val_str_ascii()
expected to get after the my_fcvt() call, so it crashed on assert.

Solution:

We cannot extend set_real() to use the my_fcvt() mode for the range of
31..38 fractional digits, because set_real() is used in a lot of places
and such a change will break everything.

Introducing String::set_fcvt() which always prints using my_fcvt()
for the whole range of decimals 0..38, supported by the FORMAT() function.

Prevents errors on Windows Linux subsystem.

Fix to pr #1600