Checked for missing synonims, added those found.

Problem was that we considered the point itself as the 'border' object. Instead
of that the 'border' of a POINT is an empty set, and the point is the 'interior'.
Another error fixed by the way - not all operations of the resulting function were properly
allocated.

Need to take into account cases of a polygon shaped as a very thin line.

The variables now return real values. They can't be made usual variables because they do not have DEFAULT value.

Problem was in reinitialization of first_successful_insert_id_in_prev_stmt_for_binlog after setting variables.

The problem is in the IsSimple function. If the first and the last points
of a curve coincide it's and exception and the line is still 'simple'.

Index names were not formatted correctly.

The 'srid' field's copying was missing in the copying Create_field::Create_field() constructor.

Merge from Percona Server enforced use of a specific storage engine
authored by Stewart Smith.

Modified to be session variable and modifiable only by SUPER. Use
similar implementation as default_storage_engine.

- Renaming Item::is_bool_func() to is_bool_type(), to avoid assumption
  that the item is an Item_func derivant.
- Deriving Item_func_spatial_rel from Item_bool_func rather than Item_int_func

fixed embedded server tests
MDEV-7009: SET STATEMENT min_examined_row_limit has no effect
MDEV-6948:SET STATEMENT gtid_domain_id = ... FOR has no effect (same for gtid_seq_no and server_id)

old values of SET STATENENT variables now saved in its own Query_arena and restored later

the problem was in assigning default value during parsing.

(changes of backported patch are very small: strlen removed, error processing fixed, view open statistics added)

Double error reporting removed.

* watch for "redefined macro" warning
* don't enable -D_FORTIFY_SOURCE=2 in debug builds (it requires -O)

common parent class for Item_func_isnull and Item_func_isnotnull

Add holder thread_id, file_name and line to output.

MDEV-7025 ANALYZE SELECT/INSERT/UPDATE/DELETE from a view does not check access permissions on the view

Added access checking for the ANALYZE statement command.

Fix Item_ident::print() to work when there is no current database

Change r_rows to be double

add forgotten initialization of the mutex name

disable a broken test, pending a proper fix