Fix the off-by-one overflow which was introduced with commit
b0fd06a6 (MDEV-15670 - unit.my_atomic failed in buildbot with
Signal 11 thrown)

Closes #1098.

The problem was in calculating of the mask to clear unused null bits in case of using full byte.

mysql_install_db.exe should not remove datadir, if it was not created by
it.

Workaround glibc bug: https://sourceware.org/bugzilla/show_bug.cgi?id=20116
by making unittest threads joinable. It makes code better anyway.

This reverts part of c5427172

Forbid ALTER DATABASE under read_only.

Closes #3

The fix for "MDEV-17698 MEMORY engine performance regression"
previously fixed this problem.

- Adding the test for MDEV-17724
- Re-recording wrong results for tests:
  * engines/iuds/r/insert_number
  * engines/iuds/r/update_delete_number
  which started to fail since MDEV-17698

Also, backporting a part of:
  MDEV-11485 Split Item_func_between::val_int() into virtual methods in Type_handler
for easier merge to 10.3.

my_read fixed as in higher versions.
my_pread made as my_read aware of partial read of huge chunks of files
MY_FULL_IO enabled for file operations

followup for c32f7ed2

reset lex->many_values for LOAD DATA, as it's used for
auto-inc range size estimation.

--gdb now accepts an argument, it will be passed to gdb as a command.
multiple commands can be separated by a (non-standard and not escapable)
delimiter - semicolon (;).

Old usage with a bare --gdb continues to work too, of course.

Cherry-picked c47c0ca5 5441bbd3 339b9055

We should clear trailing zeroes in frac part. Otherwise
that tail is growing quickly and forces unnecessary truncating of
arguments.

This reverts commit ebaacf07.

Pushed by mistake.
Broke tokudb on trusty-amd64.

test case

This reverts commit dc3a20b1.

It requires GET_BIT in include/my_getopt.h, which is available
only in 10.3+

mysql_upgrade used to convert all columns of mysql.db to
utf8_general_ci and then back to utf8_bin. In two separate ALTER's.

This failed if UNIQUE indexes in mysql.db contained entries
that differ only in the letter case.

 consistently) on Replication Slave

lower_case_table_names  0 -> 1 replication works, it's safe as long as
 mixed case names mapping to the lower case ones is one-to-one

CMP0075 Include file check macros honor CMAKE_REQUIRED_LIBRARIES

           derived table / view by equality

Now rows of a materialized derived table are always put into a
temporary table before join operation. If BNLH is used to join this
table with the result of a partial join then both operands of the
join are actually put into main memory. In most cases this is not
efficient.
We could avoid this by sending the rows of the derived table directly
to the join operation. However this kind of data flow is not supported
yet.
Fixed by not allowing usage of hash join algorithm to join a materialized
derived table if it's joined by an equality predicate of the form
f=e where f is a field of the derived table.

and followup fixes

e.g. "No option named 'FILE_KEY_MANAGEMENT_SO' in group 'ENV' at lib/My/ConfigFactory.pm line 370."
when a test has `plugin-load-add=@ENV.FILE_KEY_MANAGEMENT_SO`

more tests

fix for 2-level ft indexes and boolean search in Aria

update the code to match semantics of `key` -
it's not a (char*) pointer to the buffer as in MyISAM.

Two bugs in Aria, related to 2-level fulltext indexes:

* REPAIR calculated the key number incorrectly

* CHECK copied the key into last_key too early and
  checking the second-level btree was overwriting it