field.cc:
  BLOB variations have number-in-bytes limit,
  unlike CHAR/VARCHAR which have number-of-characters limits.
  A tinyblob column can store up to 255 bytes.
  In the case of basic Latin letters (which use 1 byte per character)
  we can store up to 255 characters in a tinyblob column.
  When passing an utf8 tinyblob column as an argument into
  a function (e.g. COALESCE) we need to reserve 3*255 bytes.
  I.e. multiply length in bytes to mbcharlen for the character set.
  Although in reality a tinyblob column can never be 3*255 bytes long,
  we need to set max_length to multiply to make fix_length_and_dec()
  of the function-caller (e.g. COALESCE) calculate the correct max_length
  for the column being created.

ctype_utf8.result, ctype_utf8.test:
  Adding test case.