Fix for MDEV-4009: main.delayed sporadically fails with "query 'REPLACE DELAYED t1 VALUES (5)' failed: 1317: Query execution was interrupted"
- Fixed broadcast without a proper mutex
- Don't break existing locks if we are just testing if we can get the lock

mysql-test/r/create_delayed.result:
  Added test case for failures with INSERT DELAYED with CREATE and DROP TABLE
mysql-test/t/create_delayed.test:
  Added test case for failures with INSERT DELAYED with CREATE and DROP TABLE
sql/mdl.cc:
  Don't break existing locks for timeout=0 (ie, just check if there are conflicting locks).
  This fixed the bug that INSERT DELAYED didn't work properly with CREATE TABLE
sql/sql_base.cc:
  One neads to hold the mutex before doing a mysql_cond_broadcast()
  This fixed the bug that INSERT DELAYED didn't work properly with DROP TABLE
sql/sql_insert.cc:
  Protect setting of mysys_var->current_mutex.

MDEV-3987 uninitialized read in Item_cond::fix_fields leads to crash: select .. where .. in ( select ... )

change Item_func_group_concat to use max_length according to the expected semantics

Remove timed mutexes in XtraDB - obsolete feature that does not link on Windows, if plugin is build dynamically
It was already  removed from innobase in the past.

Reasons:
  - as of 5.5.27, YEAR(2) is deprecated, hence the new warning;
  - MDEV-553 - different error code/message on out-of-range autoincrement;
  - INSERT IGNORE now produces a warning if a duplicate was encountered

storage_engine tests and upstream engines/* suites went out of sync with current MariaDB code. Reasons:
  - as of 5.5.27, YEAR(2) is deprecated, hence the new warning;
  - MDEV-553 - different error code/message on out-of-range autoincrement;
  - INSERT IGNORE now produces a warning if a duplicate was encountered (change pushed along with MDEV-553)

then for 5.5.28a it should be
5.5.28a-mariadb1~wheezy not 5.5.28-mariadb-a1~wheezy

MDEV-3902  Assertion `record_length == m_record_length' failed at Filesort_buffer::alloc_sort_buffer

This bug is a duplicate of mdev-3899 so adding a test case only.

  
The patch decreases the duration of LOCK_thread_count, so it is not hold during THD destructor and freeing memory.
This mutex  now only protects the integrity of threads list, when removing THD from it,  and thread_count variable.
  
The add_to_status() function that updates global status during client disconnect,  is now correctly protected by the LOCK_status mutex.

Benchmark : in a  "non-persistent" sysbench test (oltp_ro with reconnect after each query),  ~ 25% more connects/disconnects were measured

MDEV-3899  Valgrind warnings (blocks are definitely lost) in filesort on IN subquery with SUM and DISTINCT
  
Analysys:
In the beginning of JOIN::cleanup there is code that is supposed to
free all filesort buffers. The code assumes that the table being sorted
is the first non-constant table. To get this table it calls:
first_top_level_tab(this, WITHOUT_CONST_TABLES)
  
However, first_top_level_tab() instead returned the wrong table - the first
one in the plan, instead of the first non-constant table. There is no other
place outside filesort() where sort buffers may be freed. As a result, the
sort buffer was not freed, and there was a memory leak.
  
Solution:
Change first_top_level_tab(), to test for WITH_CONST_TABLES instead of
WITHOUT_CONST_TABLES.

client/mysqldump.c:
  Removed compiler warning
extra/yassl/taocrypt/include/pwdbased.hpp:
  Removed compiler warning (iterations is always unsigned)
support-files/compiler_warnings.supp:
  Ignore warnings from groff

Fixed the test to be lower-case because it fails on windows with mixed case.

mysql-test/r/create.result:
  Updated test results
mysql-test/t/create.test:
  Updated test
sql/sql_base.cc:
  Use push_internal_handler/pop_internal_handler to avoid errors & warnings instead of clear_error
  Give a warnings instead of an error for CREATE TABLE IF EXISTS
sql/sql_parse.cc:
  Check if we failed because of table exists (can only happen from create)
sql/sql_table.cc:
  Check if we failed because of table exists (can only happen from create)

Analysis:
The reason for the suboptimal plan when querying IS tables through a view
was that the view columns that participate in an equality are wrapped by
an Item_direct_view_ref and were not recognized as being direct column
references.

Solution:
Use the original Item_field objects via the real_item() method.

mysql-test/r/create.result:
  Added test case to show that CREATE TABLE also is not waiting if table exists.
mysql-test/t/create.test:
  Added test case to show that CREATE TABLE also is not waiting if table exists.
sql/sql_base.cc:
  Clear also warnings from acquire_locks if we retry.

- Added option to check_if_table_exists() to quickly check if table exists (either SHARE or .FRM)
- Extended lock_table_names() to not wait for meta data locks if CREATE IF NOT EXISTS is used.

mysql-test/r/create.result:
  New test case
mysql-test/t/create.test:
  New test case
sql/sql_base.cc:
  Added option to check_if_table_exists() to quickly check if table exists (either SHARE or .FRM)
  Extended lock_table_names() to not wait for meta data locks if CREATE IF NOT EXISTS is used.
sql/sql_base.h:
  Updated prototype
sql/sql_db.cc:
  Added extra argument to call to check_if_table_exists()

Fix of MDEV-3874: Server crashes in Item_field::print on a SELECT from a MERGE view with materialization+semijoin, subquery, ORDER BY.

The problem was that in debugging binaries it try to print item to assign human readable name to the item.
But subquery item was already freed (join_free/cleanup with full cleanup) so Item_field refers to temporary
table which memory had been already freed.

When inserting a record with update on duplicate keys the server calls
the ha_index_read_idx_map handler function to look for the record
that violates unique key constraints. The third parameter of this call
should mark only the base components of the index where the server is
searched for the record. Possible hidden components of the primary key
are to be unmarked.

Fixed typo (missing comma)

If connection kills itself (or own query), it will get an error consistently,
with both COM_PROCESSKILL and with "KILL [QUERY] id"

Assertion happened because sql_kill did not set OK status in diagnostic area
in the case of connection suicide (id to kill == thd->thread_id), issued 
via  COM_PROCESS_KILL , e.g using mysql_kill()

This patch ensures that diagnostic area is initialized in this specific case.

MDEV-736 LP:1004615 - Unexpected warnings "Encountered illegal value '' when converting to DECIMAL" on a query with aggregate functions and GROUP BY

fix: don't call field->val_decimal() if the field->is_null()
because the buffer at field->ptr might not hold a valid decimal value

sql/item_sum.cc:
  do not call field->val_decimal() if the field->is_null()
storage/maria/ma_blockrec.c:
  cleanup
storage/maria/ma_rrnd.c:
  cleanup
strings/decimal.c:
  typo