see MDEV-5981

another post-fix patch for MDEV-5850: MySQL Bug#21317: SHOW CREATE DATABASE does not obey to lower_case_table_names
(for case-insensitive filesystems)

sql/events.cc:
  for "SHOW EVENTS IN db_name"
sql/sp_head.h:
  for "CREATE EVENT", and everything SP-related
sql/sql_acl.cc:
  privilege check for mysql_change_db()
sql/sql_db.cc:
  for metadata locking of db names
sql/sql_parse.cc:
  any_db is a constant, it is not writable
sql/sql_show.cc:
  for SHOW CREATE TRIGGER and other trigger-related statements

MDEV-5971 Asymmetry between CAST(DATE'2001-00-00') to INT and TO CHAR in prepared statements

Consistently set maybe_null flag, even not-NULL temporal literal may become NULL
in the restrictive sql_mode.

fix uninit variable

Fixed that the we don't change CREATE to CREATE OR REPLACE, except if the slave removed an existing table as part of CREATE.
This will help the following replicaition scenario:
MariaDB 10.0 master (statement replication) -> MariaDB 10.0 slave (row based replication) -> MySQL or MariaDB 5.x slave


mysql-test/r/mysqld--help.result:
  Updated help text
mysql-test/suite/rpl/r/create_or_replace_mix.result:
  Added more tests
mysql-test/suite/rpl/r/create_or_replace_row.result:
  Added more tests
mysql-test/suite/rpl/r/create_or_replace_statement.result:
  Added more tests
mysql-test/suite/rpl/t/create_or_replace.inc:
  Added more tests
sql/handler.h:
  Added org_options so that we can detect what come from the query and what was possible added later.
sql/sql_insert.cc:
  Only write CREATE OR REPLACE if was originally specified or if we delete a conflicting table as part of create
sql/sql_parse.cc:
  Remember orginal create options
sql/sql_table.cc:
  Only write CREATE OR REPLACE if was originally specified or if we delete a conflicting table as part of create
sql/sys_vars.cc:
  Updated help text

            TABLE_SHARE::visit_subgraph

tc_acquire_table() is not ready to update TABLE::in_use without mutex:
thr1: table= free_tables.pop_front(); // table->in_use is 0
thr2: tdc_remove_table();
thr2: find_deadlock(); // assert(table->in_use != 0)
thr1: table->in_use= thd;

Protect update of TABLE::in_use by LOCK_table_share.

mysql.column_stats.

- Fix valgrind failure: don't touch table_list->master_had_triggers 
  when RBR_TRIGGERS is not compiled in.

post-fix patch for MDEV-5850: MySQL Bug#21317: SHOW CREATE DATABASE does not obey to lower_case_table_names

- Show a line with "Engine-independent statistics collected" when ANALYZE command
  caused EITS statistics to be recollected.

- Dont substract unsigned numbers, use correct calculations.
- (there is no testcase because effort is required to come up with it)

- Move [some] engine-agnostic tests from t/selectivity.test to t/selectivity_no_engine.test
- Move Histogram::point_selectivity to sql_statistics.cc

- Histogram::find_bucket() should not walk off the end of the value range.
- Address review feedback in Histogram::point_selectivity(): different handling
  for zero-width buckets, and explanations.

remove dead code

MDEV-5839 TokuDB tables not properly cleaned on DROP DATABASE

TokuDB does not support discover_table_names() and writes no files
in the database directory, so automatic filename-based
discover_table_names() doesn't work either. So, it must force .frm
file to disk in ::create()

Don't abort plugin reads whem mpvio->make_it_fail is set - this can leak information.

Rename back my_init_dynamic_array2() -> init_dynamic_array2()
It happens to be a part of the de facto API :(

MDEV-5955 Server crashes in handler::ha_external_lock or assertion `m_lock_type == 2' fails in handler::ha_close on disconnect with a locked temporary table

first unlock locked tables, then close and remove temporary

The reason was that a couple of variables that hold number of rows that was used to calculate buffers was uint and caused an overflow.

Fixed by changing variables that could hold number of rows from uint to ulong and also added a cast for this test.

include/heap.h:
  Reorder to get better alignment. Changed variables that could hold number of rows from uint to ulong
mysql-test/suite/heap/heap.result:
  Added test case
mysql-test/suite/heap/heap.test:
  Added test case
mysql-test/suite/plugins/t/server_audit.test:
  Added sleep as we want to have disconnect logged before we try a new connect
storage/heap/ha_heap.cc:
  Changed variables that could hold number of rows from uint to ulong
  Limit number of rows to 4G  (as most of the variables that holds rows are ulong anyway)
  reset records_changed when key_stat_version is changed to not cause increments for every row changed
storage/heap/ha_heap.h:
  changed records_changed to ulong as this can get big
storage/heap/hp_create.c:
  Changed variables that could hold number of rows from uint to ulong
  Added cast (fixed the original bug)
storage/heap/hp_delete.c:
  Changed variables that could hold number of rows from uint to ulong
storage/heap/hp_open.c:
  Removed not needed cast
storage/heap/hp_write.c:
  Changed variables that could hold number of rows from uint to ulong
support-files/compiler_warnings.supp:
  Removed extra : from supression

- Fix Histogram::point_selectivity() to work in the case where the 
  passed value_pos=0 (or 1) and the first (or the last) bucket in the 
  histogram has zero value-range (i.e one value).

[Attempt #2]
- Use a new selectivity calculation formula in Histogram::point_selectivity. 
  The formula is different from the old one because it was developed from scratch.
  it doesn't have any possible division-by-zero problems.

MDEV-5920 MySQL Bug#16765410 FTS: STACK AROUND THE VARIABLE 'MYSTR' WAS CORRUPTED IN INNOBASE_STRNXFRM

MDEV-5861 MySQL Bug#12601974 - STORED PROCEDURE SQL_MODE=NO_BACKSLASH_ESCAPES IGNORED AND BREAKS REPLICATION

escape usernames in CREATE/DROP USER error messages according to NO_BACKSLASH_ESCAPES

simplify the prototype and move it to sql_string.h

  use LEX_STRING, keep similar functions together, remove duplicated code