MDEV-21606 Improve update handler (long unique keys on blobs)
MDEV-21470 MyISAM and Aria start_bulk_insert doesn't work with long unique
MDEV-21606 Bug fix for previous version of this code
MDEV-21819 2 Assertion `inited == NONE || update_handler != this'

- Move update_handler from TABLE to handler
- Move out initialization of update handler from ha_write_row() to
  prepare_for_insert()
- Fixed that INSERT DELAYED works with update handler
- Give an error if using long unique with an autoincrement column
- Added handler function to check if table has long unique hash indexes
- Disable write cache in MyISAM and Aria when using update_handler as
  if cache is used, the row will not be inserted until end of statement
  and update_handler would not find conflicting rows.
- Removed not used handler argument from
  check_duplicate_long_entries_update()
- Syntax cleanups
  - Indentation fixes
  - Don't use single character indentifiers for arguments

- Only indentation changes in sql_rename.cc
- Ignore some WSREP error messages when there isn't a internet connection
- Force restart of stat_tables_part.test to make result stable
- Fixed compiler warnings in CONNECT

MDEV-19964 S3 replication support

Added new configure options:
s3_slave_ignore_updates
"If the slave has shares same S3 storage as the master"

s3_replicate_alter_as_create_select
"When converting S3 table to local table, log all rows in binary log"

This allows on to configure slaves to have the S3 storage shared or
independent from the master.

Other thing:
Added new session variable '@@sql_if_exists' to force IF_EXIST to DDL's.

- rename PFS specific rebind_psi() to generic rebind()
- call rebind independently of PFS compilation status
- allow rebind() return an error

MDEV-21988: Assertion failure mysqld: bool trans_commit_stmt(THD*): Assertion `thd->in_active_multi_stmt_transaction() || thd->m_transaction_psi == __null' failed. (#1476)

Set temporary `SERVER_STATUS_IN_TRANS` so assert is not triggered in `trans_commit_stmt`.

The test failed to specify default-character-set when
invoking the client. The compile-time default parameters of the
client could be overridden by configuration files in /etc/mysql.
Let us explicitly specify --default-character-set.

main.mysqlhotcopy_myisam cannot find mysqlhotcopy tool

wsrep scripts are not executable in CMAKE_CURRENT_BINARY_DIR

* generate and install mysql_config
* symlink mariadb_config (from C/C) to mariadb-config

also:
* .gitignore generated mariadb-config.1
* remove obsolete compiler flag from C/C

This reverts commit 5d1b8f41.

because since 306e439c manpages use troff aliases
instead of symlinks, so they should not be symlinked.

Drop excess jobs while still making sure there is a good variation of
running all test suites, gcc and clang versions.

Also introduce testing on architectures arm64 and ppc64le.

- Properly define build dependencies via addons/homebrew, but still keep
  secondary Homebrew run until OS X builds fully work.
- Remove references to OS X bugs that are already closed.
- As long as the OS X build does not work, it is enough to attempt to run
  just one of them, no need for many in parallel. It will just waste
  resources and slow down the job from finishing quickly.

This further simplifies and cleans up the Travis-CI file without making
any major functional changes.

With this structure .travis.yml is much easier to read and thanks to the
added documentation next developers are less likely to mess it up again
as they can more easily see how the jobs matrix work.

Number of jobs:
- before: 33 (with 7 ignored)
- after:  33 (with 7 ignored)

This partially reverts commits c12609dd and 193bc89a.

Remove unnecessary dependencies that nothing uses: dpatch libzmq-dev

Install extra build dependencies from a PPA specifically tailored for
Travis-CI use and which ensures all architectures are supported (in this
case s390x is needed and was not available from mariadb.org repos).

Validated with https://config.travis-ci.com/explore

This is first step in refactoring the Travis-CI file, which had become a
mess. This commit has no functional changes, just syntactical cleanup
and simplification.

Dependencies list has not changes, it is just sorted alphabetically so
it is easier to compare to e.g. debian/control file list.

innodb_init_params(): make sure that srv_n_log_files == 1 always

MDEV-22012 Allow SET TIMESTAMP for users with GRANT BINLOG REPLAY when --secure-timestamp=replication

when selecting from perfschema, filter out statements
used by the test istself in wait_condition.inc, because they,
by design, can be repeated unpredictable number of times.

btr_blob_free(): Compare page_id_t directly.

buf_pool_watch_unset(): Avoid unnecessarily buf_pool.mutex acquisition.

Clean up some comments as well.

Remove unnecessary buf_pool_t:: qualifiers. In comments,
replace buf_pool::mutex with buf_pool.mutex.

Remove an outdated comment about a planned buffer pool resizing feature.
It is already implemented in MariaDB 10.2.2 (and MySQL 5.7.9).

- mbmaxlen is always 0 for binary field. Ignore the assert of checking
field->prefix_len % field->col->mbmaxlen == 0.

fix manpages in Debian

To change all executables to have a mariadb name I had to:
- Do name changes in every CMakeLists.txt that produces executables
- CREATE_MARIADB_SYMLINK was removed and GET_SYMLINK added by Wlad to reuse the function in other places also
- The scripts/CMakeLists.txt could make use of GET_SYMLINK instead of introducing redundant code, but I thought I'll leave that for next release
- A lot of changes to debian/.install and debian/.links files due to swapping of real executable and symlink. I did not however change the name of the manpages, so the real name is still mysql there and mariadb are symlinks.
- The Windows part needed a change now when we made the executables mariadb -named. MSI (and ZIP) do not support symlinks and to not break backward compatibility we had to include mysql named binaries also. Done by Wlad

my_atomic.h is included indirectly anyways.

The code that commit bb24fa31
moved to a separate file assume_aligned.h was introduced in
commit 25e2a556 and developed
by employees of MariaDB Corporation.