Backporting MDEV-15597 Add class Load_data_outvar and avoid using Item::STRING_ITEM for Item_user_var_as_out_param detection

This is a part of "MDEV-18045 Backporting the MDEV-15497 changes to 10.2 branch"

This is a part of "MDEV-18045 Backporting the MDEV-15497 changes to 10.2 branch"

This is a part of "MDEV-18045 Backporting the MDEV-15497 changes to 10.2 branch"

Since MySQL 5.6.16 (and MariaDB Server 10.0.11), changes of
buf_page_t::buf_fix_count are atomic memory operations if
PAGE_ATOMIC_REF_COUNT is defined. Since MySQL 5.7
(and MariaDB Server 10.2.2), the field is always updated
by atomic memory operations.

In a few occurrences, updates of the counter were unnecessarily
surrounded by an acquisition and release of the block mutex
(buf_block_t::mutex or buf_pool_t::zip_mutex). Remove these
unnecessary mutex operations.

Use fprintf(stderr) instead of msg() to print the version line

but even if this script called as /bin/mysql_install_db
it is still standard install and scripts are in /usr/share/
(but not in the /share/)
2. fix of bindir path

trx_rseg_t::is_persistent(): Correct a bogus debug assertion.

log_group_read_log_seg(): Always return false when returning
before reading end_lsn.

xtrabackup_copy_logfile(): On error, indicate whether
a corrupt log record was encountered.

Only xtrabackup_copy_logfile() in Mariabackup cared about the
return value of the function. InnoDB crash recovery was not
affected by this bug.

By pure chance the macro worked in the cases it was used, but
better to get this fixed!

dict_create_foreign_constraints_low(): Clean up the way in
which the error messages are initialized, and ensure that
the table name is always initialized.

Fix incremental prepare to copy #rocksdb subdirectory from the
incremental dir.

The variable is obsolete.
In mariabackup --backup, encryption plugin loading code sets the value
this parameter to the same as in server.

In mariabackup --prepare, no new redo  log is generated,
and xtrabackup_logfile is removed after it anyway.

cmake/submodules: notify user about gitconfig for automatic update

Co-Authored-By: grooverdan <daniel@linux.ibm.com>

Most of the mtr tests in the galera_3nodes suite fail
for a variety of reasons with a variety of errors.

This patch fixes several substantial flaws
in the galera_3nodes suite tests and in the mtr framework
service files, adapting the tests from galera_3nodes
for the current version of MariaDB.

This patch also synchronizes some galera_3nodes-related
files with the latest changes made for MDEV-17835 (v2 patch)
and for MDEV-18379 in other branches (10.2 and 10.3).

Closes #1161

The code path where the table was not being rebuilt during ALTER TABLE
was not covered by the test. Add coverage, and remove the debug assertion
that could fail in this case.

Followup for db8f0dae

and in fef9013d

fixes memory leaks in restart_mysqld.inc tests

Followup for 8f5ea83f

MDEV-18426: Most of the mtr tests in the galera_3nodes suite fail

Most of the mtr tests in the galera_3nodes suite fail
for a variety of reasons with a variety of errors.
Some tests simply need to add the missing "connection"
lines to the result files, but many of them fail due
to substantial errors that require reworking test files.

This patch adds the missing "connection" lines to
the result files and fixes several substantial flaws
in the galera_3nodes suite tests and in the mtr framework
service files, adapting the tests from galera_3nodes
for the current version of MariaDB.

https://jira.mariadb.org/browse/MDEV-18426