Analysis: Problem was that actual payload size (page size) after compression
was handled incorrectly on encryption. Additionally, some of the variables
were not initialized.

Fixed by encrypting/decrypting only the actual compressed page size.

MDEV-8268: InnoDB: Assertion failure in file buf0buf.cc line 5842 failing assertion ut_a(free_slot != NULL);

Analysis: Problem is that there is not enough temporary buffer slots
for pending IO requests.

Fixed by allocating same amount of temporary buffer slots as there
are max pending IO requests.

Removed memcpy's on cases when page is not encrypted and make sure
we use the correct buffer for reading/writing.

- Make ANALYZE correctly remember and report filesort() calls
- Temp.table use is collected but only basic info is reported.

MDEV-8250: InnoDB: Page compressed tables are not compressed and compressed+encrypted tables cause crash

Analysis: Problem is that both encrypted tables and compressed tables use
FIL header offset FIL_PAGE_FILE_FLUSH_LSN_OR_KEY_VERSION to store
required metadata. Furhermore, for only compressed tables currently
code skips compression.

Fixes:
- Only encrypted pages store key_version to FIL header offset FIL_PAGE_FILE_FLUSH_LSN_OR_KEY_VERSION,
  no need to fix
- Only compressed pages store compression algorithm to FIL header offset FIL_PAGE_FILE_FLUSH_LSN_OR_KEY_VERSION,
  no need to fix as they have different page type FIL_PAGE_PAGE_COMPRESSED
- Compressed and encrypted pages now use a new page type FIL_PAGE_PAGE_COMPRESSED_ENCRYPTED and
  key_version is stored on FIL header offset FIL_PAGE_FILE_FLUSH_LSN_OR_KEY_VERSION and compression
  method is stored after FIL header similar way as compressed size, so that first
  FIL_PAGE_COMPRESSED_SIZE is stored followed by FIL_PAGE_COMPRESSION_METHOD
- Fix buf_page_encrypt_before_write function to really compress pages if compression is enabled
- Fix buf_page_decrypt_after_read function to really decompress pages if compression is used
- Small style fixes

return unsigned, not signed.
return a value large enough for GCM

and don't recommend aes_ctr if it's unavailable

introduce ENCRYPTION_KEY_SYSTEM_DATA and
ENCRYPTION_KEY_TEMPORARY_DATA constants; use them everywhere.

IO_CACHE tempfiles encryption

when working with IO_CACHE's, don't access IO_CACHE::file directly

* remove unused (and not implemented) WRITE_NET type
* remove cast in my_b_write() macro. my_b_* macros are
  function-like, casts are responsibility of the caller
* replace hackish _my_b_write(info,0,0) with the explicit
  my_b_flush_io_cache() in my_b_write_byte()
* remove unused my_b_fill_cache()
* replace pbool -> my_bool
* make internal IO_CACHE functions static
* reformat comments, correct typos, remove obsolete comments (ISAM)
* assert valid cache type in init_functions()
* use IO_ROUND_DN() macro where appropriate
* remove unused DBUG_EXECUTE_IF in _my_b_cache_write()
* remove unnecessary __attribute__((unused))
* fix goto error in parse_file.cc
* remove redundant reinit_io_cache() in uniques.cc
* don't do reinit_io_cache() if the cache was not initialized
  in ma_check.c
* extract duplicate functionality from various _my_b_*_read
  functions into a common wrapper. Same for _my_b_*_write
* create _my_b_cache_write_r instead of having if's in
  _my_b_cache_write (similar to existing _my_b_cache_read and
  _my_b_cache_read_r)
* don't call mysql_file_write() from my_b_flush_io_cache(),
  call info->write_function() instead

that is, don't create a "temporary" IO_CACHE with file==-1
and manually swap it later to the valid file descriptor.

remove some 14-year old code that added support for
LOAD DATA replication to IO_CACHE:
* three callbacks, of which only two were actually used and that
  were only needed for LOAD DATA replication but were
  tested in every IO_CACHE instance
* an additional opaque void * argument in IO_CACHE, also only
  used for LOAD DATA replication, but present everywhere
* the code to close IO_CACHE prematurely in LOAD DATA to have
  these callbacks called in the correct order and a long
  comment explaining what will happen if IO_CACHE is not
  closed prematurely
* a variable to track whether IO_CACHE was closed prematurely
  (to avoid double-closing it)

perfschema after 5.6 merge depends on sql_yacc.h

To make st_select_lex::master_unit() inlinable:
- moved it's definition to sql_lex.h
- removed base class virtual master_unit() declaration since this method is
  specific to st_select_lex

Overhead change:
st_select_lex::master_unit()      0.17% -> out of radar
execute_sqlcom_select()           0.13% -> 0.12%
JOIN::save_explain_data_intern()  0.27% -> 0.23%
JOIN::optimize_inner()            0.76% -> 0.72%
JOIN::exec_inner()                0.30% -> 0.24%
JOIN::prepare()                   0.30% -> 0.29%
JOIN::optimize()                  0.05% -> 0.05%

Moved THD::set_command() definition to sql_class.h so that it can be inlined.

Overhead change:
THD::set_command        0.05% -> out of radar

Moved THD::set_query() definition to sql_class.h so that it can be inlined.

Overhead change:
THD::set_query       0.07% -> out of radar

MDEV-8257 Erroneous "Impossible where" when mixing decimal comparison and LIKE

ulong is not portable - different width on different architectures

version_ssl_library should show the version
of openssl library that is being used, not the one
that server was compiled with.

don't run this test on 1.0.1c

Use quote_for_equal to correctly escape characters.

mysqldump now attempts to make use of the INFORMATION_SCHEMA tables.
If the table name is not found with a case sensitive search, it
fallbacks to a case insensitive search.

MDEV-8241: Debug build on Windows is broken: error LNK2019: unresolved external symbol pthread_detach referenced in function ma_checkpoint_init

pthread_detach() replaced with pthread_detach_this_thread()

pthread_detach_this_thread() definition fixed