Add Modern Perl headers. Perl 5.16 is still fairly
old from 2012.

Enable UTF-8, warnings and make script 'strict'

Small fixes for perlcritic reported problems and some crashes

I/O layer ":utf8" used at line 268, column 16.  Use ":encoding(UTF-8)" to get strict validation.  (Severity: 5)
"return" statement with explicit "undef" at line 806, column 4.  See page 199 of PBP.  (Severity: 5)
"return" statement with explicit "undef" at line 6844, column 4.  See page 199 of PBP.  (Severity: 5)
"return" statement with explicit "undef" at line 7524, column 4.  See page 199 of PBP.  (Severity: 5)
"return" statement with explicit "undef" at line 7527, column 4.  See page 199 of PBP.  (Severity: 5)
"return" statement with explicit "undef" at line 7599, column 4.  See page 199 of PBP.  (Severity: 5)
"return" statement with explicit "undef" at line 7602, column 4.  See page 199 of PBP.  (Severity: 5)
Expression form of "eval" at line 7784, column 4.  See page 161 of PBP.  (Severity: 5)
Expression form of "eval" at line 7806, column 4.  See page 161 of PBP.  (Severity: 5)
Glob written as <...> at line 8016, column 25.  See page 167 of PBP.  (Severity: 5)
"return" statement followed by "sort" at line 9195, column 60.  Behavior is undefined if called in scalar context.  (Severity: 5)
Expression form of "eval" at line 9846, column 10.  See page 161 of PBP.  (Severity: 5)

buf_read_page_low(): Remove an error message and a debug assertion
that can be triggered when using innodb_page_size=4k and
innodb_file_per_table=0. In that case, buf_read_ahead_linear()
may be invoked on page 255, which is one less than the first
page of the doublewrite buffer (256).

fil_space_t::flush_freed(): Renamed from buf_flush_freed_pages();
this is a backport of aa458506 from 10.6.
Invoke log_write_up_to() on last_freed_lsn, instead of avoiding
the operation when the log has not yet been written.
A more costly alternative would be that log_checkpoint() would invoke
this function on every affected tablespace.

buf_read_ahead_linear(): Correct some calculations that were broken
in commit b1ab211d (MDEV-15053).

Thanks to Daniel Black for providing a test case and initial debugging.

Tested by: Matthias Leich

btr_cur_need_opposite_intention(): Check also page_zip_available()
so that we will escalate to exclusive index latch when a non-leaf
page may have to be split further due to ROW_FORMAT=COMPRESSED page
overflow.

Tested by: Matthias Leich

best_access_path(): Simplify the logic for computing fanout.
This fixes up commit 4329ec5d

Command lsof can fail on Debian install.
Revert logic more like old one to make sure that there is no failing
and still does don't boundce on shellcheck.

Debian install scripts if-clauses are not formatted
as they should be. This commit formats Debian
Pre and Post script if-clauses.

Commit fixes several ShellCheck found problems in Debian
Pre- and Postscripts.

Debian script mariadb-server-10.6.postrm contains shellcheck
Fixed problems are:
  https://www.shellcheck.net/wiki/SC2166 -- Prefer [ p ] && [ q ] as [ p -a q...
  https://www.shellcheck.net/wiki/SC2006 -- Use $(...) notation instead of le...
  https://www.shellcheck.net/wiki/SC1091 -- Not following: /usr/share/debconf...

Debian script mariadb-server-10.6.postinst contains shellcheck
Fixed problems are:
  https://www.shellcheck.net/wiki/SC2129 -- Consider using { cmd1; cmd2; } >>...
  https://www.shellcheck.net/wiki/SC1091 -- Not following: /usr/share/debconf...
  https://www.shellcheck.net/wiki/SC1072 -- Expected test to end here (don't ...
  https://www.shellcheck.net/wiki/SC1073 -- Couldn't parse this test expressi...
  https://www.shellcheck.net/wiki/SC1009 -- The mentioned syntax error was in...

Debian script mariadb-server-10.6.preinst contains shellcheck
Fixed problems are:
  https://www.shellcheck.net/wiki/SC2231 -- Quote expansions in this for loop...
  https://www.shellcheck.net/wiki/SC2166 -- Prefer [ p ] && [ q ] as [ p -a q...
  https://www.shellcheck.net/wiki/SC2001 -- See if you can use ${variable//se...
  https://www.shellcheck.net/wiki/SC1091 -- Not following: /usr/share/debconf...
  https://www.shellcheck.net/wiki/SC1007 -- Remove space after = if trying to...

There is several misindentation inside Debian post and pre
installation scripts. False indentation with space
as indent space should be 2 and indentation with tabs.

Derived table creation code would call Field::make_new_field() which would
memcpy the Field object from the source table, including Field::read_stats.

But the temp. table as a whole had table->stats_is_read=false. Which was
correct but not consistent with Field::read_stats and caused an assertion.

Fixed by making sure that Field::read_stats=NULL for fields in the new
temporary (i.e. work) tables.

The problem, introduced in patch for MDEV-26301:

When check_join_cache_usage() decides not to use join buffer, it must
adjust the access method accordingly. For BNL-H joins this means switching
from pseudo-"ref access"(with index=MAX_KEY) to some other access method.

Failing to do this will cause assertions down the line when code that is
not aware of BNL-H will try to initialize index use for ref access with
index=MAX_KEY.

The fix is to follow the regular code path to disable the join buffer for
the join_tab ("goto no_join_cache") instead of just returning from
check_join_cache_usage().

Do not try to decide merge/materialize for derived if it was already decided
(even if it is a view).

RocksDB (in a submodule) has to include <cstdint> to use uint64_t
but it doesn't. Until the submodule is upgraded, let's replace
problematic types with something that's available

select_insert::store_values() must reset
has_value_set bitmap before every row, just like mysql_insert() does.
because ON DUPLICATE KEY UPDATE and triggers modify it

Temporary fix to avoid the server crash.

Add Optimizer Trace printouts.

This patch optimizes the number of refills for the lateral derived table
to which a materialized derived table subject to split optimization is
is converted. This optimized number of refills is now considered as the
expected number of refills of the materialized derived table when searching
for the best possible splitting of the table.

(part 1 is in the previous commit)
to [ pass ] galera.MDEV-18832, galera.MDEV-27862