A partial backport of 67f21fb3a077dedfd14b9ca720e926c55e682f93,
Bug#22283790: RANGE OPTIMIZER UTILIZES TOO MUCH MEMORY WITH MANY OR CONDITIONS

The backported part changes SEL_TREE::keys from being an array of
MAX_KEY elements (64*8=512 bytes) to a Mem_root_array<SEL_ARG*> (32 bytes +
alloc'ed array of as many elements as we need).

The patch doesn't fix the "not limiting memory" part, but the memory usage
is much lower with it.

utf8mb4_thai_520_w2, ucs2_thai_520_w2, utf16_thai_520_w2, utf32_thai_520_w2

  from ctype_uca.test. This is to reuse ctype_thai.inc for other Unicode
  character sets later
- Removing separate ctype_uca.result

  and including it from t/ctype_uca.test
- Deleting r/ctype_uca_th.result

They have bytes 0x25 and 0x5F. Testing that these bytes are treated as parts
of multi-byte characters rather than underscore and percent sign.

Mark gssapi plugin as stable. No open bug reports, and no further work planned, thus stable is accurate

- Changing strnxfrm_multiply from 8 to 4, as agreed with Pruet Boonma
- Adjusting tests

When simplify_joins() converts an outer join to an inner, it should
reset the value of TABLE::dep_tables.  This is needed, because the
function may have already set TABLE::dep_tables according to the outer
join dependency.

don't use MY_THREAD_SPECIFIC on the client side
in embedded:
1. server memory accounting does not track client
   side memory
2. in not embedded builds, this still *might* be
   useful for plugins (handlersocket, connect, etc)

including the test case:

https://github.com/mysql/mysql-server/commit/520aedfe
INNODB: "DATA DIRECTORY" OPTION OF CREATE TABLE FAILS WITH PWRITE() OS
ERROR 22
Fix for version mysql-5.6
PROBLEM
========
For version mysql-5.6.27 onwards InnoDB fails to create a table
with explicit 'data directory' option when Innodb_flush_method
is set to O_DIRECT.While creating link file we get a  a pwrite
error 22 due to the alignment restrictions imposed by O_DIRECT
flag  which is being set for the link file created.

FIX
===
Fixed the above issue by making use of file IO functions while
creating the link file that wouldn't let the O_DIRECT flag
restrictions arise.
Reviewed-by: Kevin Lewis <kevin.lewis@oracle.com>
Reviewed-by: Shaohua Wang <shaohua.wang@oracle.com>
RB: 11387

Do not allow NULL password to pass directly to password
validation plugin.

An additional warning saying "tc-log cannot be enabled"
is emitted when InnoDB is installed at runtime on mysqld
built with wsrep-patch (-DWITH_WSREP=ON).

This happens because, installing InnoDB increments the
total number of 2pc-capable engines and with wsrep-patch
already enabled - the total count goes >1. Even though,
this condition is sufficient to enable tc-logging, it is
not permitted at runtime, and thus the warning.

Updated the testcase to avoid the warning.

Ha_trx_info should not be reset in ha_fake_trx_id() as it is
later used during commit.

This is to ensure that the list of valid values for
METADATA_LOCK_INFO fields is always kept in sync with
the parent MDL types.

Xtrabackup-based SST method uses socat. Move it from
Suggests to Depends list.

10.1 introduced a problem:
Execution time for various recursive stages
(walk, update_used_table, and propagate_equal_fields)
in NULLIF is O(recursion_level^2), because complexity is
doubled on every recursion level when we copy args[0] to args[2].

This change fixes to avoid unnecessary recursion in:
- Item_func_nullif::walk
- Item_func_nullif::update_used_tables
- Item_func_nullif::propagate_equal_fields
when possible.

         CREATE function.

         Test case added.

take MDL_SHARED_WRITE instead of MDL_SHARED_NO_READ_WRITE
for OPTIMIZE TABLE. For engines that need a stronger
lock (like MyISAM), reopen the table with
MDL_SHARED_NO_READ_WRITE.

Two bugs here:
* the server could create an frm (with a long attribute
  value) that it could not read back
* Connect engine opened files from inside DROP TABLE
  and was ignoring the error (correctly) but was not
  hiding it from the server (incorrectly). This caused
  a crash later when DROP TABLE was finishing successfully
  while stmt_da already have seen an error.

Also added a text case for
  MDEV-7935 CREATE TABLE ... AS SELECT ... can cause a Server crash (Assertion `0' in Protocol::end_statement)
because Connect stopped clearing the error status
in stmt_da as a fix for MDEV-7935

* my_yyabort_error() helper
* s/lex->thd/thd/
* remove 'else' after MYSQL_YYABORT (for consistency,
  95% of the parser did not use 'else' in this case)
* simplify ER_SLAVE_HEARTBEAT_VALUE_OUT_OF_RANGE

when reading table options

install private generated files

Do not mark subquery as inexpensive when it is not optimized.