remove old deprecation helpers that were not used anywhere.

create new deprecation helpers and enforce their usage

this also removes inconsistencies in reporting deprecation:
sometimes it was ER_WARN_DEPRECATED_SYNTAX (1287),
sometimes ER_WARN_DEPRECATED_SYNTAX_NO_REPLACEMENT (1681),
sometimes a warning, sometimes a note.

it should always be
* ER_WARN_DEPRECATED_SYNTAX
* a warning (because it's something actionable, not purely informational)

after fb175a1b

it was introduced in ff8651c4 to suppress deprecated
warnings for CALL under the flawed logic that "It's doesn't
make sense to print out deprecated syntax warnings when the
routine is being executed because this kind of warning only
matters when the routine is being created".

Which is incorrect, a feature might become deprecated after
the routine was created and a user has to know that to be able
to update the procedure before it stops working when a
deprecated feature is removed.

mark non-default values of old_mode as deprecated.
print a warning when they're set from the command line and in SQL.

In particular:

* @@debug
  deprecated since 5.5.37
* sr_YU locale
  deprecated since 10.0.11
* "engine_condition_pushdown" in the @@optimizer_switch
  deprecated since 10.1.1
* @@date_format, @@datetime_format, @@time_format, @@max_tmp_tables
  deprecated since  10.1.2
* @@wsrep_causal_reads
  deprecated since 10.1.3
* "parser" in mroonga table comment
  deprecated since 10.2.11

KDF(key_str, salt [, {info | iterations} [, kdf_name [, width ]]])

kdf_name is "hkdf" or "pbkdf2_hmac" (default).

width (in bits) can be any number divisible by 8,
by default it's taken from @@block_encryption_mode

iterations must be positive, and is 1000 by default

OpenSSL 1.0 doesn't support HKDF, so it'll return NULL.
This OpenSSL version is still used in SLES 12 and CentOS 7

like ErrConvString, but puts the string in 'single quotes'

followup for 7ba9c7fb

* don't introduce random four-space-gaps into the middle of description
  (meaning, nicely aligned wrapped string in the code gets ugly
  in the rpm)
* remove obsolete comment
* MariaDB-connect-engine is a required package for MariaDB-connect-engine-jdbc
  not "recommended"
* don't recommend both mariadb-java-client and mysql-connector-java
* in fact, don't recommend anything, it works badly for old rpm < 4.13,
  installs something that user may not want, and install redundand deps.
  Let's rethink how to do it meaningfully. And not break tests.

followup for 7ba9c7fb

Not ready yet, it fails its own test suite

This reverts commit 485c9b1f

first seen in daca468c

Commit 738d4604 changed component name
from "backup" to "Backup". Use the new name now.

Fix the Cache_flip_event_log constructor.

- optimize atomic store64/load64 implementation.
- allow CRC32 optimization. Do not allow pmull yet, as this fails like in
  https://stackoverflow.com/questions/54048837/how-to-perform-polynomial-multiplication-using-arm64

- Removing two copies of the drop_routine.
  Adding a shared and much simplified version.

- Removing LEX metods:
      bool stmt_drop_function(const DDL_options_st &options,
                              const Lex_ident_sys_st &db,
                              const Lex_ident_sys_st &name);

      bool stmt_drop_function(const DDL_options_st &options,
                              const Lex_ident_sys_st &name);

      bool stmt_drop_procedure(const DDL_options_st &options,
                               sp_name *name);

  The code inside the methods was very similar.
  Adding one method instead:

      bool stmt_drop_routine(const Sp_handler *sph,
                          const DDL_options_st &options,
                          const Lex_ident_sys_st &db,
                          const Lex_ident_sys_st &name);

- Adding a new virtual method Sp_handler:sqlcom_drop().
  It helped to unify the code inside the new stmt_drop_routine().

Resolving the shift/reduce conflict conflict in:

GRANT ..  ON /*ambiguity*/ FUNCTION f1 TO foo@localhost;
GRANT ... ON /*ambiguity*/ [TABLE] function TO foo@localhost;

and in

REVOKE ..  ON /*ambiguity*/ FUNCTION f1 TO foo@localhost;
REVOKE ... ON /*ambiguity*/ [TABLE] function TO foo@localhost;

using a new %prec directive.

ibuf_bitmap_buffered(): A new predicate, to check if the
IBUF_BITMAP_BUFFERED bit for a particular page is set.

ibuf_merge(): If ibuf_bitmap_buffered() does not hold,
skip the records for the page. One reason why we might have
this situation is the bug that was fixed in
commit 34c283ba (MDEV-32132).

Fixed tests:
main.flush_corruption - disabled service connection for some queries
since it is necessary that the query SELECT pass in the same session

This test does not work in embedded and I cannot see an obvious way of fixing that. The test not running in embedded is not the end of the world here.

Problem:
Under terms of MDEV-27490, we'll update Unicode version used
to compare identifiers to 14.0.0. Unlike in the old Unicode version,
in the new version a string can grow during lower-case. We cannot
perform check_db_name() inplace any more.

Change summary:

- Allocate memory to store lower-cased identifiers in memory root

- Removing check_db_name() performing both in-place lower-casing and validation
  at the same time. Splitting it into two separate stages:
  * creating a memory-root lower-cased copy of an identifier
    (using new MEM_ROOT functions and Query_arena wrapper methods)
  * performing validation on a constant string
    (using Lex_ident_fs methods)

Implementation details:

- Adding a mysys helper function to allocate lower-cased strings on MEM_ROOT:

    lex_string_casedn_root()

  and a Query_arena wrappers for it:

    make_ident_casedn()
    make_ident_opt_casedn()

- Adding a Query_arena method to perform both MEM_ROOT lower-casing and
  database name validation at the same time:

    to_ident_db_internal_with_error()

  This method is very close to the old (pre-11.3) check_db_name(),
  but performs lower-casing to a newly allocated MEM_ROOT
  memory (instead of performing lower-casing the original string in-place).

- Adding a Table_ident method which additionally handles derived table names:

    to_ident_db_internal_with_error()

- Removing the old check_db_name()

(Review input addressed)
(Added handling of UPDATE/DELETE and partitioning w/o index)

If the properties of the used collation allow, do the following
equivalent rewrites:

1. UPPER(key_col)=expr  ->  key_col=expr
   expr=UPPER(key_col)  ->  expr=key_col
   (also rewrite both sides of the equality at the same time)

2. UPPER(key_col) IN (constant-list)  -> key_col IN (constant-list)

- Mark utf8mb{3,4}_general_ci as collations that allow this.
- Add optimizer_switch='sargable_casefold=ON' to control this.
  (ON by default in this patch)
- Cover the rewrite in Optimizer Trace, rewrite name is
  "sargable_casefold_removal".

sys_shrink_buffer_pool to make it as generic name.

- Updated capabilities for PostgreSQL in server.cfg
- Updated test-ATIS & test-table-elimination to work with PostgreSQL
- Updated test-transaction test to also work with non transactional tables

Other things:
- Added test of tables with many keys in test-insert
- Added 2 new GROUP BY .. ORDER BY test

This works the same as secure-file-priv="", but is more obvious way to
turn of secure-file-priv.

avoid deprecation warning

- Moving get_canonical_filename() from a public function to a method in handler.
- Adding a helper method is_canonical_filename() to handler.
- Adding helper methods left(), substr(), starts_with() to Lex_cstring.
- Adding helper methods is_sane(), buffer_overlaps(),
  max_data_size() to CharBuffer.
- Adding append_casedn() to CharBuffer. It implements the main functionality
  that replaces the being removed my_casedn_str() call.
- Adding a class Table_path_buffer,
  a descendant of CharBuffer with size FN_REFLEN.
- Changing get_canonical_filename() to get a pointer to Table_path_buffer
  instead just a pointer to char.
- Changing the data type of the "path" parameter and the return type of
  get_canonical_filename() from char* to Lex_cstring.

1. "mariabackup --innobackupex" now prints a new warning:
       '--innobackupex' is deprecated and will be removed in a future release

2. "mariabackup --innobackupex" does not print this wrong warning any more:
        --innobackupex: Deprecated program name.
          It will be removed in a future release,
          use '/path/to/mariadb-backup' instead