adding test case.
item_cmpfunc.cc:
  Bug#12611
  ESCAPE + LIKE do not work when the escape char is a multibyte one
  Additional fix for 8bit character sets:
  escape character must be converted into
  operation character set.


sql/item_cmpfunc.cc:
  Bug#12611
  ESCAPE + LIKE do not work when the escape char is a multibyte one
  Additional fix for 8bit character sets:
  escape character must be converted into
  operation character set.
mysql-test/t/func_like.test:
  adding test case.
mysql-test/r/func_like.result:
  adding test case.