- Hook window function computation into the right location.
- Add a testcase which shows that HAVING is now checked before
  the window function computation step.

- Make EXPLAIN code use the post-join operations
- Remove Sort_and_group_tracker that was used for that purpose

man page updates: mysqlbinlog options, mysqlcheck clarification and 10.2 updates

We can call setup_partition_border_check() from
JOIN::make_aggr_tables_info(), provided that call is made after
appropriate set_items_ref_array() call.

gbh != NULL is handled in a separate branch above,
we don't get into this part of code when gbh!=NULL

Added class Window_funcs_computation, with setup() method to setup
execution, and exec() to run window function computation.

setup() is currently trivial. In the future, it is expected to optimize
the number of sorting operations and passes that are done over the temp.
table.

as it can return negative values.
The typo was introduced in the patch for MDEV-9665 in 10.2.0.

as they are not used any more.
We now use function templates from strcoll.ic instead.

Fixed calculating pointer to memory allocated for names in numeric format in unpacking procedure.

Item_func_or_sum.
Implemented method update_used_tables for class Item_findow_func.
Added the flag Item::with_window_func.
Made sure that window functions could be used only in SELECT list
and ORDER BY clause.
Added test cases that checked different illegal placements of
window functions.

- Make Item_XXX::cleanup() clean List<Cached_item> orderby_fields.
  (Items survive across PS re-executions. Cached_item don't, because
   they keep pointers to fix_field'ed items, etc)
- Move List<Cached_item> out into Group_bound_tracker.

this fixes 40 failures in mysql-test

Added --thread_cache_size=0 to some tests that was depending on not having
a thread cache.

Added --thread_cache_size=0 to slow_launch_time_func.test as otherwise
the new thread would start too fast to be counted as a slow_launch_thread.

between gbk_chinese_ci and big5_chinese_ci.

> commit e0929951
> Author: Alexander Barkov <bar@mariadb.org>
> Date:   Wed Mar 16 10:55:12 2016 +0400
>
>     MDEV-9665 Remove cs->cset->ismbchar()
>     Using a more powerfull cs->cset->charlen() instead.

        The cause of the issue is when DROP DATABASE takes
        metadata lock and is in progress through it's
        execution, a concurrently running CREATE FUNCTION checks
        for the existence of database which it succeeds and then it
        waits on the metadata lock.  Once DROP DATABASE writes to
        BINLOG and finally releases the metadata lock on schema
        object, the CREATE FUNCTION waiting on metadata lock
        gets in it's code path and succeeds and writes to binlog.

1. Fixing Field_time::get_equal_const_item() to pass TIME_FUZZY_DATES
   and TIME_INVALID_DATES to get_time_with_conversion().
   This is needed to make the recursively called Item::get_date() return
   non-NULL values on garbage input. This makes Field_time::get_equal_const_item()
   work consistently with how Item::val_time_packed() works.

2. Fixing Item::get_date() to return TIME'00:00:00' rather than
   DATE'0000-00-00' on empty or garbage input when:
   - TIME_FUZZY_DATES is enabled
   - The caller requested a TIME value (by passing TIME_TIME_ONLY).
   This is needed to avoid conversion of DATE'0000-00-00' to TIME
   in get_time_with_conversion(), which would erroneously try to subtract
   CURRENT_DATE from DATE'0000-00-00' and return TIME'-838:59:59' rather than
   the desired zero value TIME'00:00:00'.

   #1 and #2 fix these type of scripts to return one row with both
   MyISAM and InnoDB, with and without an index on t1.b:

     CREATE TABLE t1 (a ENUM('a'), b TIME, c INT, KEY(b));
     INSERT INTO t1 VALUES ('','00:00:00',0);
     SELECT * FROM t1 WHERE b='';
     SELECT * FROM t1 WHERE a=b;
     SELECT * FROM t1 IGNORE INDEX(b) WHERE b='';
     SELECT * FROM t1 IGNORE INDEX(b) WHERE a=b;

   Additionally, #1 and #2 fix the originally reported in MDEV-9604 crash
   in Item::save_in_field(), because now execution goes through a different
   path, so save_in_field() is called for a Item_time_literal instance
   (which is non-NULL) rather than a Item_cache_str instance (which could
   return NULL without setting null_value).

3. Fixing Field_temporal::get_equal_const_item_datetime() to enable
   equal field propagation for DATETIME and TIMESTAMP in case of
   comparison (e.g. when ANY_SUBST), for symmetry with
   Field_newdate::get_equal_const_item(). This fixes a number of problems
   with empty set returned on comparison to empty/garbage input.
   Now all SELECT queries in this script return one row for MyISAM and InnoDB,
   with and without an index on t1.b:

     CREATE TABLE t1 (a ENUM('a'), b DATETIME, c INT, KEY(b));
     INSERT INTO t1 VALUES ('','0000-00-00 00:00:00',0);
     SELECT * FROM t1 WHERE b='';
     SELECT * FROM t1 WHERE a=b;
     SELECT * FROM t1 IGNORE INDEX(b) WHERE b='';
     SELECT * FROM t1 IGNORE INDEX(b) WHERE a=b;

Added 5 minute timeout before automaticlally removing threads from thread
cache.

This solves a problem with jemalloc, which is slow with a small
thread cache and also makes thread_cache big enough that most users
doesn't have to touch it

filesort and init_read_record() for the same table.
This will simplify code for WINDOW FUNCTIONS (MDEV-6115)

- Filesort_info renamed to SORT_INFO and moved to filesort.h
- filesort now returns SORT_INFO
- init_read_record() now takes a SORT_INFO parameter.
- unique declaration is moved to uniques.h
- subselect caching of buffers is now more explicit than before
- filesort_buffer is now reusable even if rec_length has changed.
- filsort_free_buffers() and free_io_cache() calls are removed
- Remove one malloc() when using get_addon_fields()

Other things:
- Added --debug-assert-on-not-freed-memory option to make it easier to
  debug some not-freed-memory issues.