In spatial indexes there can be only one keyseg.
Make it explicit in the code, don't pretend that this can work
with the arbitrary number of keysegs.

and FIELDFLAG_xxx constants

prefer x->field over table->field[x->field->field_index]

only use my_print_error when the error message is not
ER(error_code)

the stage is changed from 'old_stage' to 'new_stage',
not the other way around

and partition_info::set_show_version_string - they were
already broken and impossible to maintain

unused freshly initialized record should be trashed
with TRASH_ALLOC, not TRASH_FREE

remove redundant method

also, return different values for different errors in my_addr_resolve()

MDEV-11075: Power - runtime detection of optimized instructions

Signed-off-by: Daniel Black <daniel.black@au.ibm.com>

        The weird logic of json_contains was implemented.

WL#7682 in MySQL 5.7 introduced the possibility to create light-weight
temporary tables in InnoDB. These are called 'intrinsic temporary tables'
in InnoDB, and in MySQL 5.7, they can be created by the optimizer for
sorting or buffering data in query processing.

In MariaDB 10.2, the optimizer temporary tables cannot be created in
InnoDB, so we should remove the dead code and related data structures.

This was originally part of MDEV-11487.

Adjust some results and error codes.

        Support for '**' in json path expressions added.