Spider patches 026 (MDEV-7723), 031 (MDEV-7727) and 058 (MDEV-12532)

This allows the storage engine to internally compute sum and count
operations.

- Enhance sum items to be able to store the sum value directly.
- return_record_by_parent() is enabled in spider as
  HANDLER_HAS_DIRECT_AGGREGATE is defined
- Added spd_environ.h to spider. This is loaded first to ensure that all
  MariaDB specific defines that are used by include files are properly
  defined.
- This code is tested by the existing spider tests direct_aggregate.test
  and direct_aggregate_part.test and also partition.test

Done to simplify spider patch for direct aggregates

Other things:
- Cleanup of allocated bitmaps done in open(), which
  simplifies init_partition_bitmaps()
- Add needed defines in ha_spider.cc to enable new spider code
- Fixed some DBUG_PRINT() to be consistent with normal code
- Removed end space
- The changes in test cases partition_innodb, partition_range,
  partition_pruning etc are becasue partitions can now more exactly
  calculate the number of rows in a range.

Contains spider patches:
014,015,023,033,035,037,040,042,044,045,049,050,051,053,059

Allow partition engines to access table->s->connect_string for engines
that uses HTON_CAN_READ_CONNECT_STRING_IN_PARTITION
Don't reset table->s->connect_string in ha_partition::open

Added Spider patches:
003_mariadb-10.0.15.vp.diff
060_mariadb-10.2.0.partition_reset_top_table_fields.diff

- Support HA_EXTRA_ADD_CHILDREN_LIST,HA_EXTRA_ATTACH_CHILDREN,
  HA_EXTRA_IS_ATTACHED_CHILDREN and HA_EXTRA_DETACH_CHILDREN
  in partition handler for handlers that has HA_CAN_MULTISTEPL_MERGE flag
- Added HA_CAN_MULTISTEPL_MERGE to MERGE handler.
- Added handler::get_child_handlers()
- Change m_num_lock to contain total number of locks. This was needed as
  we now adjust number of locks when extra(HA_EXTRA_ATTACH_CHILDREN) is
  called.

- Enable HA_EXTRA_WRITE_CAN_REPLACE and HA_EXTRA_WRITE_CANNOT_REPLACE for
  partition engine.

- Added cond_push() and cond_pop() to ha_partition.cc

013_mariadb-10.0.15.vp_handler.diff
034_mariadb-10.0.15.vp_handler2.diff
005_mariadb-10.0.15.hs.diff
041_mariadb-10.0.15.vp_handler2.diff
+ Fixes from Kentoku
+ Added handler/suite.pm and handler/suite.opt to be able to run test cases
  in spider/handler

Also changed Unique row not found to use uppercase first.
This was done to make these messages consistent with the rest

- mysql_install_db now prints position to error file, if log-error is used
- Warning about compatibility now mentions MySQL 5.6 and 5.7
- Give warning if --show_compatibility_56 is used

This was done to make thing consistent. It gives the additional benefit
that EXPLAIN EXTENDED now treat null_tables like constant's and replaces
columns with NULL, in a similar way that it replaces columns with constants
for constant tables.

- Null tables are tables where all columns are always NULL. The most common
  NULL TABLE is a table used in a LEFT_JOIN that is never true.
- All result changes comes from replacing columns with NULL for null_tables.
- "Impossible where" is now also shows constants for const columns.
- Removed duplicated s->type= JT_CONST
- Reset found_const_table_map when JOIN is created (safety fix)

srv_purge_wakeup(): If thd_destructor_proxy has initiated the first
step of shutdown, ensure that all purge threads terminate.

logs_empty_and_mark_files_at_shutdown(): Add a debug assertion.
(The purge threads should have been shut down already before this step.)

(possibly intermittent) checksum mismatch.

trx_set_rw_mode() is never called for read-only transactions, this is guarded
by callers.

Removing this condition from critical section immediately gives 5% scalability
improvement in OLTP index updates benchmark.

is detected.

The checksum mismatch can be due to partial write, thus retry the read

From comment in unreg.h:

  Types of values in the MariaDB extra2 frm segment.
  Each value is written as
    type:       1 byte
    length:     1 byte  (1..255) or \0 and 2 bytes.
    binary value of the 'length' bytes.

length == 1 is valid.

Window is a reserved keyword according to SQL Standard 2016. However, we
can make the grammar slightly flexible by allowing WINDOW keyword everywhere
except table aliases. Change yacc grammar to separate between all keywords
and table_alias keywords.

1. Removing data type specific constants from enum_item_param_state,
   adding SHORT_DATA_VALUE instead.
2. Replacing tests for Item_param::state for the removed constants to
   tests for Type_handler::cmp_type() against {INT|REAL|TIME|DECIAML}_RESULT.
   Deriving Item_param::PValue from Type_handler_hybrid_field_type,
   to store the data type handler of the current value of the parameter.

3. Moving Item_param::decimal_value and Item_param::str_value_ptr
   to Item_param::PValue. Adding Item_param::PValue::m_string
   and changing Item_param to use it to store string values,
   instead of Item::str_value. The intent is to replace Item_param::value
   to a st_value based implementation in the future, to avoid duplicate code.
   Adding a sub-class Item::PValue_simple, to implement
   Item_param::PValue::swap() easier.
   Remaming Item_basic_value::fix_charset_and_length_from_str_value()
   to fix_charset_and_length() and adding the "CHARSET_INFO" pointer
   parameter, instead of getting it directly from item->str_value.charset().
   Changing Item_param to pass value.m_string.charset() instead
   of str_value.charset().
   Adding a String argument to the overloaded
   fix_charset_and_length_from_str_value() and changing Item_param
   to pass value.m_string instead of str_value.

4. Replacing the case in Item_param::save_in_field() to a call
   for Type_handler::Item_save_in_field().

5. Adding new methods into Item_param::PValue:
   val_real(), val_int(), val_decimal(), val_str().
   Changing the corresponding Item_param methods
   to use these new Item_param::PValue methods
   internally. Adding a helper method
   Item_param::can_return_value() and removing
   duplicate code in Item_param::val_xxx().

6. Removing value.set_handler() from Item_param::set_conversion()
   and Type_handler_xxx::Item_param_set_from_value().
   It's now done inside Item_param::set_param_func(),
   Item_param::set_value() and Item_param::set_limit_clause_param().

7. Changing Type_handler_int_result::Item_param_set_from_value()
   to set max_length using attr->max_length instead of
   MY_INT64_NUM_DECIMAL_DIGITS, to preserve the data type
   of the assigned expression more precisely.

8. Adding Type_handler_hybrid_field_type::swap(),
   using it in Item_param::PValue::swap().

9. Moving the data-type specific code from
   Item_param::query_val_str(), Item_param::eq(),
   Item_param::clone_item() to
   Item_param::value_query_type_str(),
   Item_param::value_eq(), Item_param::value_clone_item(),
   to split the "state" dependent code and
   the data type dependent code.
   Later we'll split the data type related code further
   and add new methods in Type_handler. This will be done
   after we replace Item_param::PValue to st_value.

10. Adding asserts into set_int(), set_double(), set_decimal(),
   set_time(), set_str(), set_longdata() to make sure that
   the value set to Item_param corresponds to the previously
   set data type handler.

11. Adding tests into t/ps.test and suite/binlog/t/binlog_stm_ps.test,
   to cover Item_param::print() and Item_param::append_for_log()
   for LIMIT clause parameters.
   Note, the patch does not change the behavior covered by the new
   tests. Adding for better code coverage.

12. Adding tests for more precise integer data type in queries like this:
    EXECUTE IMMEDIATE
     'CREATE OR REPLACE TABLE t1 AS SELECT 999999999 AS a,? AS b'
      USING 999999999;
    The explicit integer literal and the same integer literal
    passed as a PS parameter now produce columns of the same data type.
    Re-recording old results in ps.result, gis.result, func_hybrid_type.result
    accordingly.

- get rid of casts between int and HANDLE.
- store file descriptor in TP_connection_generic to get
rid of multiple mysql_socket_getfd(c->thd->net.vio->mysql_socket))

Also support named pipes (no reason not to support, since it is easy)

UT_RELAX_CPU() is supposed to waste a few CPU cycles, there's no need to
load other system components.

Server already has HMT_low/HMT_medium.

gcc_sync.h, solaris.h, generic-msvc.h copied verbatim.

mariabackup fails to builds with PFS disabled. The reason was missing include,
which was included by PFS otherwise.