In this statement:

  (uint *) thd->alloc(sizeof(uint) * field->interval->count+1);

parentheses around the '+' operator were missing. So too few memory
was allocated, which caused ASAN builds to fail on these tests:

  innodb.innodb-ucs2
  parts.part_ctype_utf32
  main.mix2_myisam_ucs2
  main.case
  main.ctype_ucs
  main.ctype_utf16
  main.ctype_utf16_uca
  main.ctype_utf16le

Fixed to a correct version with parentheses:

  (uint *) thd->alloc(sizeof(uint) * (field->interval->count+1));