Changed Travis status to show status of branch 10.5 (it was still pointing to 10.4)

[Variant 2 of the fix: collect the attached conditions]

Problem:
make_join_select() has a section of code which starts with
 "We plan to scan all rows. Check again if we should use an index."

the code in that section will [unnecessarily] re-run the range
optimizer using this condition:

  condition_attached_to_current_table AND current_table's_ON_expr

Note that the original invocation of range optimizer in
make_join_statistics was done using the whole select's WHERE condition.
Taking the whole select's WHERE condition and using multiple-equalities
allowed the range optimizer to infer more range restrictions.

The fix:
- Do range optimization using a condition that is an AND of this table's
condition and all of the previous tables' conditions.
- Also, fix the range optimizer to prefer SEL_ARGs with type=KEY_RANGE
over SEL_ARGS with type=MAYBE_KEY, regardless of the key part.
Computing
key_and(
  SEL_ARG(type=MAYBE_KEY key_part=1),
  SEL_ARG(type=KEY_RANGE, key_part=2)
)
will now produce the SEL_ARG with type=KEY_RANGE.

class log_file_t: more or less sane RAII wrapper around redo log file
descriptor and its path.

This change is motivated by the need of using that log_file_t somewhere else.

We missed these in commit 89633995
and commit ccd87d34.

MDEV-21490: binlog tests fail with valgrind: Conditional jump or move depends on uninitialised value in sql_ex_info::init

Problem:
=======
P1) Conditional jump or move depends on uninitialised value(s)
    sql_ex_info::init(char const*, char const*, bool) (log_event.cc:3083)

code: All the following variables are not initialized.
----
  return ((cached_new_format != -1) ? cached_new_format :
    (cached_new_format=(field_term_len > 1 || enclosed_len > 1 ||
    line_term_len > 1 || line_start_len > 1 || escaped_len > 1)));

P2) Conditional jump or move depends on uninitialised value(s)
    Rows_log_event::Rows_log_event(char const*, unsigned
      int, Format_description_log_event const*) (log_event.cc:9571)

Code: Uninitialized values is reported for 'var_header_len' variable.
----
  if (var_header_len < 2 || event_len < static_cast<unsigned
      int>(var_header_len + (post_start - buf)))

P3) Conditional jump or move depends on uninitialised value(s)
    Table_map_log_event::pack_info(Protocol*) (log_event.cc:11553)

code:'m_table_id' is uninitialized.
----
  void Table_map_log_event::pack_info(Protocol *protocol)
  ...
  size_t bytes= my_snprintf(buf, sizeof(buf), "table_id: %lu (%s.%s)",
                              m_table_id, m_dbnam, m_tblnam);

Fix:
===
P1 - Fix)
Initialize cached_new_format,field_term_len, enclosed_len, line_term_len,
line_start_len, escaped_len members in default constructor.

P2 - Fix)
"var_header_len" is initialized by reading the event buffer. In case of an
invalid event the buffer will contain invalid data. Hence added a check to
validate the event data. If event_len is smaller than valid header length
return immediately.

P3 - Fix)
'm_table_id' within Table_map_log_event is initialized by reading data from
the event buffer. Use 'VALIDATE_BYTES_READ' macro to validate the current
state of the buffer. If it is invalid return immediately.

this test needs a *server* and tries to connect with $MYSQL to it

PCRE reports small frame size working with ASAN, so the test has to be ready
for the minimlas possible size.

os_file_flush_data_func(): fix builds on POSIX OSs where fdatasync()
is not avaiable

log_t::files::flush_data_only(): rename from fdatasync()

log_t::files::fsync(): removed and replaced with flush_data_only().
It will flush everything we need for using redo log files.

This is the only symlink in the repository. Symlinks can cause
trouble when using file systems or operating systems that do not
support them.

Also remove the unused file DartConfig.cmake that refers to the script.

cmake -DWITH_INNODB_EXTRA_DEBUG:BOOL=ON
was broken ever since commit 8777458a
(MDEV-6076 Persistent AUTO_INCREMENT for InnoDB).

There is a race condition between page reads that call
page_zip_validate() (while holding clustered index root page S-latch)
and writes that update PAGE_ROOT_AUTO_INC
(with buf_block_t::lock SX-latch, compatible with S-latch).

page_zip_validate_low(): Skip the PAGE_ROOT_AUTO_INC field on
clustered index root pages in order to avoid false positives.

MDEV-21551 :  Assertion `m_active_threads.size() >= m_long_tasks_count + m_waiting_task_count' failed"

Happened when running innodb_fts.sync_ddl

m_long_task_count could be wrongly reset to 0, if m_task_queue is
empty.

dict_table_t::parse_name(): Properly calculate the *tbl_name_len.

A failure was easily repeatable during the test
innodb.innodb-alter-debug for the table name test.① ("test/@2460").
The UTF-8 representation of the U+2460 is only 3 bytes "\xe2\x91\xa0"
while the filename-safe encoded counterpart of it in dict_table_t::name
is 5 bytes "@2460".

This bug, introduced by commit ea37b144
(MDEV-16678), could cause a purge task to hang.

Post-push fix. aria_pack_mdev14183 test is unstable.

The fix is the following:
1. Disable the test for embedded server.
2. Create non-"transactional" Aria table in the test, as aria_pack does not
support "transactional" Aria tables.

tests for --ssl-verify-server-cert with system CA
and with incorrect hostname

While waiting for mutex, thread_pool_generic::wait_begin(),
current task can be marked long-running. This is done by periodic
mantainence task, that runs in parallel.

Fix to recheck is_long_task() after the mutex acquisition.

I found that memcpy_aligned was used incorrectly at redo log and decided to put
assertions in aligned functions. And found even more incorrect cases.

Given the amount discovered of bugs, I left assertions to prevent future bugs.

my_assume_aligned(): instead of MY_ASSUME_ALIGNED macro

This is 10.4 version.

Idea is to create monitor thread for both donor and joiner that will
periodically if needed extend systemd timeout while SST is being
processed. In 10.4 actual SST is executed by running SST script
and exchanging messages on pipe using blocking fgets. This fix
starts monitoring thread before SST script is started and
we stop monitoring thread when SST has been completed.

Made the test order_by_pack_big stable

An assertion added in commit c20bf8fd
includes a sign mismatch. Make the affected data members unsigned.

Since commit f52bf920 the type
Sql_sort is non-trivial, because it includes a data member
Bounds_checked_array<SORT_FIELD> local_sortorder.
There still is no vtable, so memset() is safe to invoke, but
we must add a cast to silence a warning in GCC 8 or later.

MDEV-21541: main.sum_distinct-big fails with Assertion `m_buffer_end == __null || end <= m_buffer_end'

For Merge_chuck structures first set the start and end positions of the buffer and
then adjust the end positions of the buffer if the records are dynamic in nature.

- Adding a way to define I_S columns without DEFAULT.
- Fixing all ENUM columns in I_S.INNODB* table definitions to have no DEFAULT.

maybe_wake_or_create_thread()

A task that is executed,could be counted as waiting (after wait_begin()
before wait_end()) or as long-running (callback runs for a long time).

If task is both marked waiting and long running, then calculation of
current concurrency (# of executing tasks - # of long tasks - #of waiting tasks)
is wrong, as task is counted twice.

Thus current concurrency could go negative, but with unsigned arithmetic
it will become a huge number.

As a result, maybe_wake_or_create_thread() would neither wake or create
a thread, when it should. Which may result in a deadlock.

Someone tried -DBUILD_SHARED_LIBS:BOOL=ON. This did not work well