There was no way to repair corrupt ARCHIVE data file,
when unrecoverable data loss is inevitable.

With this fix REPAIR ... EXTENDED attempts to restore
as much rows as possible, ignoring unrecoverable data.

Normal REPAIR is still able to repair meta-data file
only.

mysql-test/r/archive.result:
  A test case for BUG#46565.
mysql-test/std_data/bug46565.ARZ:
  A test case for BUG#46565.
mysql-test/std_data/bug46565.frm:
  A test case for BUG#46565.
mysql-test/t/archive.test:
  A test case for BUG#46565.
storage/archive/ha_archive.cc:
  Allow unrecoverable data loss when extended repair
  is requested.