MDEV-3818: Query against view over IS tables worse than equivalent query without view

Fixed the test to be lower-case because it fails on windows with mixed case.
Fixed some compiler warnings
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.
MDEV-3945 - do not hold LOCK_thread_count when freeing THD.
  
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-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.
if the debian package name for 5.5.28 is 5.5.28-mariadb1~wheezy
then for 5.5.28a it should be
5.5.28a-mariadb1~wheezy not 5.5.28-mariadb-a1~wheezy
typo
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)
MDEV-3990: engine tests 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
MDEV-3993  - add MSI installer option to set character-set-server=utf8