The conn_kind, which stands for "connection kind", is no longer useful
because the HandlerSocket support is deleted and Spider now has only
one connection kind, SPIDER_CONN_KIND_MYSQL. Remove conn_kind and
related code.
Signed-off-by: Yuchen Pei <yuchen.pei@mariadb.com>
Reviewed-by: Nayuta Yanagisawa <nayuta.yanagisawa@mariadb.com>

Produced using the following command

unifdef -UITEM_FUNC_TIMESTAMPDIFF_ARE_PUBLIC -m storage/spider/spd_*
Signed-off-by: Yuchen Pei <yuchen.pei@mariadb.com>
Reviewed-by: nayuta.yanagisawa@mariadb.com

unifdef -DSPIDER_FIELD_FIELDPTR_REQUIRES_THDPTR -m
storage/spider/*.{cc,h}

and removing the definition manually.
Signed-off-by: Yuchen Pei <yuchen.pei@mariadb.com>
Reviewed-by: Nayuta Yanagisawa <nayuta.yanagisawa@mariadb.com>

spider_rewrite plugin is not in 11.0. spider initialization code used
"11.0" for "in the distant future", but suddenly it's now

spider tests didn't expect anything beyond 10.x

commit_try_rebuild(): Only invoke trx_t::drop_table_statistics()
if both InnoDB statistics tables are accessible (and exclusively
locked by the current transaction). This avoids a crash due to
ut_a(sym_node->table != NULL) in pars_retrieve_table_def().

The crash was repeated on a partial copy of a MariaDB 10.3 data
directory that lacked the *.ibd files for the statistics tables.

fil_space_t::flush<false>(): If the CLOSING flag is set,
the file may already have been closed, resulting in EBADF
being returned by fdatasync(). In any case, the
thread that had set the flag should take care of invoking
os_file_flush_func().

The crash occurred during the execution of FLUSH TABLES...FOR EXPORT.

Tested by: Matthias Leich

Also refer to the service file for startup.

Also include the ftp.mariadb.org script rather than old name.

This turns out to be a too expensive call to use for every freed page,
especially under global buffer pool mutex protection.

Also, the usefulness of proactive shrinking of the buffer pool on Windows
this is seems questionable - there is no OOM killer, and the OS will
shrink working sets itself.

This fixes up 25b91c3f