index doesn't return correct result
item_cmpfunc.cc:
  Use charset of LIKE to decide whether
  to use 8bit or Unicode "escape" value.
  But use charset of "escape" to scan escape character.
strings/ctype-xxx.c:
  We cannot reduce "end" pointer using charpos(),
  because of possible escape characters in the string.
  Limit the loop using count of written characters instead.
ctype_like_escape.inc:
  new file
mysql-test/t/ctype_xxx:
mysql-test/r/ctype_xxx:
  Adding test case.