MDEV-11127 : Fix innochecksum to work with large files on Windows.
MDEV-11127 : Fix innochecksum to work with large files on Windows.

- don't use stat() for file size, it doesn not handle large size
  use GetFileSizeEx() instead

- don't use lseek(), it can't handle large files, use _lseeki64() instead.

- Also, switch off OS file buffering for innochecksum on Windows,
to avoid thrashing file cache.

flynn1973/mariadb-aix,natsys/mariadb_10.2,flynn1973/mariadb-aix,natsys/mariadb_10.2,natsys/mariadb_10.2,flynn1973/mariadb-aix,flynn1973/mariadb-aix,natsys/mariadb_10.2,natsys/mariadb_10.2,flynn1973/mariadb-aix,flynn1973/mariadb-aix,natsys/mariadb_10.2,natsys/mariadb_10.2,flynn1973/mariadb-aix,natsys/mariadb_10.2,flynn1973/mariadb-aix,flynn1973/mariadb-aix,flynn1973/mariadb-aix,natsys/mariadb_10.2,flynn1973/mariadb-aix,natsys/mariadb_10.2,natsys/mariadb_10.2