Part6: Deriving Item_type_holder from Type_handler_hybrid_real_field_type

referenced_by_foreign_key2(), needed for InnoDB to compile,
was taken from 10.0-galera

- Added mem_root to all calls to new Item
- Added private method operator new(size_t size) to Item to ensure that
  we always use a mem_root when creating an item.

This saves use once call to current_thd per Item creation

Conflicts:
	client/mysql_upgrade.c
	mysql-test/r/func_misc.result
	mysql-test/suite/binlog/r/binlog_stm_mix_innodb_myisam.result
	mysql-test/suite/innodb/r/innodb-fk.result
	mysql-test/t/subselect_sj_mat.test
	sql/item.cc
	sql/item_func.cc
	sql/log.cc
	sql/log_event.cc
	sql/rpl_utility.cc
	sql/slave.cc
	sql/sql_class.cc
	sql/sql_class.h
	sql/sql_select.cc
	storage/innobase/dict/dict0crea.c
	storage/innobase/dict/dict0dict.c
	storage/innobase/handler/ha_innodb.cc
	storage/xtradb/dict/dict0crea.c
	storage/xtradb/dict/dict0dict.c
	storage/xtradb/handler/ha_innodb.cc
	vio/viosslfactories.c

- Changed ER(ER_...) to ER_THD(thd, ER_...) when thd was known or if there was many calls to current_thd in the same function.
- Changed ER(ER_..) to ER_THD_OR_DEFAULT(current_thd, ER...) in some places where current_thd is not necessary defined.
- Removing calls to current_thd when we have access to thd

Part of this is optimization (not calling current_thd when not needed),
but part is bug fixing for error condition when current_thd is not defined
(For example on startup and end of mysqld)

Notable renames done as otherwise a lot of functions would have to be changed:
- In JOIN structure renamed:
   examined_rows -> join_examined_rows
   record_count -> join_record_count
- In Field, renamed new_field() to make_new_field()

Other things:
- Added DBUG_ASSERT(thd == tmp_thd) in Item_singlerow_subselect() just to be safe.
- Removed old 'tab' prefix in JOIN_TAB::save_explain_data() and use members directly
- Added 'thd' as argument to a few functions to avoid calling current_thd.

This is MDEV-7601, including it's sub tasks MDEV-7594, MDEV-7555, MDEV-7590, MDEV-7581, MDEV-7589

The problem was that select_lex->non_agg_fields was not properly reset for re-execution and this caused an overwrite of a random memory position.
The fix was move non_agg_fields from select_lext to JOIN, which is properly reset.

Added THD argument to select_result and all derivative classes.
This reduces number of pthread_getspecific calls from 796 to 776 per OLTP RO
transaction.

Provide basic info about sorting/grouping done by the queries.

Conflicts:
	.bzrignore
	VERSION
	cmake/plugin.cmake
	debian/dist/Debian/control
	debian/dist/Ubuntu/control
	mysql-test/r/join_outer.result
	mysql-test/r/join_outer_jcl6.result
	mysql-test/r/null.result
	mysql-test/r/old-mode.result
	mysql-test/r/union.result
	mysql-test/t/join_outer.test
	mysql-test/t/null.test
	mysql-test/t/old-mode.test
	mysql-test/t/union.test
	packaging/rpm-oel/mysql.spec.in
	scripts/mysql_config.sh
	sql/ha_ndbcluster.cc
	sql/ha_ndbcluster_binlog.cc
	sql/ha_ndbcluster_cond.cc
	sql/item_cmpfunc.h
	sql/lock.cc
	sql/sql_select.cc
	sql/sql_show.cc
	sql/sql_update.cc
	sql/sql_yacc.yy
	storage/innobase/buf/buf0flu.cc
	storage/innobase/fil/fil0fil.cc
	storage/innobase/include/srv0srv.h
	storage/innobase/lock/lock0lock.cc
	storage/tokudb/CMakeLists.txt
	storage/xtradb/buf/buf0flu.cc
	storage/xtradb/fil/fil0fil.cc
	storage/xtradb/include/srv0srv.h
	storage/xtradb/lock/lock0lock.cc
	support-files/mysql.spec.sh