When compiling with a default key block size greater than the
smallest key block size used in a table, checking that table
failed with bogus errors. The table was marked corrupt. This
affected myisamchk and the server.

The problem was that the default key block size was used at
some places where sizes less or equal to the block size of the
index in check was required.

We do now use the key block size of the particular index
when checking.

A test case is available for later versions only.


myisam/mi_check.c:
  Bug#22119 - Changing MI_KEY_BLOCK_LENGTH makes a wrong myisamchk
  Changed check_k_link() and chk_index_down() to use the block
  size of the index in check or MI_MIN_KEY_BLOCK_LENGTH where
  required. Formerly myisam_block_size or MYISAM_SHARE::blocksize
  was used wrongly.