threads but never removes them

When wsrep_slave_threads is changed at runtime, the old "change"
value is not taken into account and thus successive SETs can
make wsrep_slave_threads value inconsistent with the actual
number of applier threads present.

* bzr merge -r3980..3984 codership-mysql/5.5
* bzr merge -r3985..3997 codership-mysql/5.5
* Fixed a segfault.
* Modified wsrep.variables test & fixed a warning
  in mtr script.

Updated wsrep.variables test.

if galera library is not specified or found.

- When range optimizer cannot the lookup value into [VAR]CHAR(n) column,
  it should produce:
  = "Impossible range" for equality
  = "no range" for non-equalities.

"have_warnings" was set to an uninialized value when converting
a negative number to datetime.

MDEV-6099 Bad results for DATE_ADD(.., INTERVAL 2000000000000000000.0 SECOND)
MDEV-6097 Inconsistent results for CAST(int,decimal,double AS DATETIME)
MDEV-6100 No warning on CAST(9000000 AS TIME)

We have to run the derived table prepare before the unique table check to mark the derived table (in this case the unique table check can turn that table to materialized one).

use -ggdb3 if supported

  Bug #18167356: EXPLAIN W/ EXISTS(SELECT* UNION SELECT*)
                 WHERE ONE OF SELECT* IS DISTINCT FAILS.

the bugfix itself was not merged - MariaDB doesn't have this bug.

mysql_derived_merge() made correctly working with views.

Added the EXCEPTIONS-CLIENT (that was lost in the merge),
as the ascii version of http://www.mysql.com/about/legal/licensing/foss-exception/

MDEV-6281 Typo in mysql_install_db scripts
and collateral changes:

* remove mysql_tableinfo.1 and references to it (there's no mysql_tableinfo)
* for debian: create manpages for mysqlrepair, mysqlanalyze, mysqloptimize
  (as symlinks for mysqlcheck.1, just as executables are symlinks to mysqlcheck)
* remove mysqlmanager.8 and references to it
* correct "very long line" error in mysqladmin.1
* simplify and fix table formatting in mysqlbinlog.1 and mysqldump.1
* fix a typo in the help text in mysql_install_db
* aria_chk: say "for Linux on x86_64", like other tools do
  (not "for Linux at x86_64")
* add simple manpages for aria_* utilities

- Make partition pruning work for tables inside semi-join nests
  (the new condition is the same that range optimizer uses so 
   it should be ok)

- When the optimizer chose LooseScan, make_join_readinfo() should
  use the index that was chosen for LooseScan, and should not try 
  to find a better (shortest) index.

The bug was in the mysqltest.c. It didn't check the send_query result
properly, so when that fails and the thread gets disconnected,
it goes unnoticed, so the consequitive read_result call crashes.
Fixed by checking the sernd_query return.

back to 3.8.3.