that introduced engine independent persistent statistics.
In particular:
- added an enumeration type for possible values of the system
  variable use_stat_tables
- renamed KEY::real_rec_per_key to KEY::actual_rec_per_key
- optimized the collection of statistical data for any primary
  key defined only on one column.
  

If a query referenced some system statistical tables, but not all of them,
then executing an ANALYZE command simultaneously with this query could
lead to a deadlock.
The fix prohibited reading statistics from system statistical tables
for such queries.

Removed the function unlock_tables_n_open_system_tables_for_write()
as not used anymore.
Performed some minor refactoring of the code in sql_statistics.cc. 

engine-independent statistics.
If a table was created for InnoDB then the execution of the
ANALYZE command over this table blocked any INSERT/DELETE/UPDATE
of the table. 

engine-independent statistics.
When the primary key was dropped or changed statistics on secondary
indexes for the prefixes that included components of the primary 
key was not removed from the table mysql.index_stats.

Also fixed: in the some cases when a column was changed statistics
on the indexes that included this column was not removed from the
table mysql.index_stats.

Also disabled the test mdev-504 for --ps-protocol.

1. The PERSISTENT FOR clause of the ANALYZE command overrides
the setting of the system variable use_stat_tables: 
with this clause ANALYZE unconditionally collects persistent
statistics.
2. ANALYZE collects persistent statistics only for tables of
the USER category. So it never collects persistent statistics
for system tables.  

The adjustment was supposed to be done in the previous commit.

  table_stat  -> table_stats
  column_stat -> column_stats
  index_stat  -> index_stats
to be in line with the names of innodb statistical tables 
from mysql-5.6: innodb_table_stats and innodb_index_stats.

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.

The invalid implementation of the method Field_bit::cmp_max could
trigger a valgrind complain or could lead to incorrect statistical
data when collecting engine-independent statistics on BIT fields.

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

Fix some problems in the TC_LOG_MMAP commit processing, which could
lead to assertions in some cases.

Problems are mostly reproducible in MariaDB 10.0 with asynchroneous
commit checkpoints, but most of the problems were present in earlier
versions also.

Adjust unstable test case.

Properly drop all unused keys.
Patch by Igor Babaev.

mysql_config:
- add not only $pkgincludedir, but also $pkgincludedir/.. to the header search path,
  for #include <mysql/plugin.h> to work


scripts/mysql_config.sh:
  - don't support headers in */include anymore. only in */include/mysql
  - remove the incorrect "bug fix" (fixed correctly long time ago)
  - add not only $pkgincludedir, but also $pkgincludedir/.. to the header search path,
    for #include <mysql/plugin.h> to work
  - but don't do it, if $pkgincludedir/.. is /usr/include

followup fixes for MySQL Bug #13889741: HANDLE_FATAL_SIGNAL IN _DB_ENTER_ | HANDLE_FATAL_SIGNAL IN STRNLEN

Take into account that length of strings passed down to this function can be up to FN_REFLEN+1 bytes. including terminating zero.
The overwrite was caused by incomplete fix to MySQL Bug # 44834

If triggers are used for an insert/update/delete statement than the values of
all virtual columns must be computed as any of them may be used by the triggers.

add a test case for MySQL Bug #13889741: HANDLE_FATAL_SIGNAL IN _DB_ENTER_ | HANDLE_FATAL_SIGNAL IN STRNLEN

  
The problem is that memory alocated by copy_andor_structure() well be freed,
but if level of SELECT_LEX it will be excluded (in case of merge derived tables and view)
then sl->where/having will not be updated here but still can be accessed (so it will be access to freed memory).

(patch by Sanja)