don't transform Item_func_nullif if it's context_analysis_only

when calculating COUNT(basic_const), take into account that
this basic_const may be NULL

This fixes
MDEV-9538 Server crashes in check_show_access on SHOW STATISTICS
MDEV-9539 Server crashes in make_columns_old_format on SHOW GEOMETRY_COLUMNS
MDEV-9540 SHOW SPATIAL_REF_SYS and SHOW SYSTEM_VARIABLES return empty results with numerous warnings

when doing set_field_to_new_field (from switch_to_nullable_trigger_fields())
make sure that the field we're about to change actually belongs
to the right table (otherwise we cannot dereference new_field[]
array as the wrong table might have more fields than
new_field[] has elements)

Case: table with a NOT NULL field, BEFORE UPDATE trigger,
and UPDATE with a subquery that uses GROUP BY on that
NOT NULL field, and needs a temporary table for it.

Because of the BEFORE trigger, the field becomes nullable
temporarily. But its Item_field (used in GROUP BY) doesn't.
When working with the temptable some code looked at
item->maybe_null, some - at field->null_ptr.
The fix: make Item_field nullable when its field is.

This triggers an assert. The group key size is calculated
before the item is made nullable, so the group key doesn't
have a null byte. The fix: make fields/items nullable
before the group key size is calculated.

when replicating old temporal type fields (that don't store
metadata in the binlog), take the precision from
destination fields.

(this fixes the replication failure, crashes were
fixed in a different commit)

it's *display length* (a.k.a. field_length)
not storage length (a.k.a. pack_length)

* make a local variable for target_table->field[col]
* move an often-used bit function to my_bit.h
* remove a non-static and not really needed trivial comparison
  function with a very generic name

to avoid run-time libjemalloc.so dependency
link binary tarballs with a static libjemalloc_pic.a

(-DWITHOUT_SERVER=1)

The filter command did not accept characters . [ ] which are valid
in an attribute name for a sphinx query with json filtering.

+ test case added

BLES (in CREATE_OPTIONS column)

MDEV-9833 - fix mysql_config --libs for weird cases, where mysqlclient link dependencies contain  flags instead of libraries (like  -pthread rather than -lpthread)

Restoring currect_select fixed.

Adjusted INSTALL_LIBDIR detection so that it is set to "lib64" on any 64bit
system (not only x86_64). New condition is insipired by GNUInstallDirs cmake
module.

MDEV-9559: Server without encryption configs crashes if selecting from an implicitly encrypted table

There was two problems. Firstly, if page in ibuf is encrypted but
decrypt failed we should not allow InnoDB to start because
this means that system tablespace is encrypted and not usable.
Secondly, if page decrypt is detected we should return false
from buf_page_decrypt_after_read.

MDEV-9557 - fix compilation errors due to missing krb5_free_unparsed_name() in old versions of Heimdal Kerberos

Patch originally by Codarren Velvindron

Revert the patch for MDEV-9504.
It causes test failures, attempt to fix these causes more failures. The
source of all this is that the code in test_if_skip_sort_order() has
a peculiar way of treating select_limit parameter:
Correct value is computed when the query plan is changed. In other cases,
we use an approximation that ignores the presence of GROUP BY clause,
or JOINs, or both.

A patch that fixes all of the above would be too big to do in 10.1

The memory loss could happen in Aria with encrypted tables when Aria failed to encrypt a block.
In normal usage this should never happen.

Conflicts:
	configure.cmake

create_partition_index_description() had wrong logic to calculate
length of the key value buffer that is used by the range optimizer.

For some reason it used MAX(partitioning_columns_len,
subpartitioning_columns_len) while it should use SUM of these values.

- Legacy code would set JOIN_TAB::limit only for EXPLAIN queries (this
  variable is only used when producing EXPLAIN output)

- ANALYZE/SHOW EXPLAIN need to produce EXPLAIN output for non-EXPLAIN
  queries, too, so we should always set JOIN_TAB::limit.

Conflicts:
	config.h.cmake
	configure.cmake

Conflicts:
	configure.cmake

The check for UCONTEXT in cmake was somehow become broken, disabling the
fallback to ucontext. This caused the non-blocking client API to not be
available for non-x86 platforms, on which no hand-crafted assembler
implementation of my_context is available.

DBUG_ASSERT() added in the patch for MDEV-9181 did not take into account
special circumstances for the prepared statement EXECUTE. Fixig the assert.
Also, extending and fixing comments made during MDEV-9181.

The test restarts the server, it should not be executed for embedded