replace wild_case_compare with my_wildcmp which is multibyte safe function


mysql-test/r/lowercase_utf8.result:
  test result
mysql-test/t/lowercase_utf8-master.opt:
  test case
mysql-test/t/lowercase_utf8.test:
  test case
sql/sql_show.cc:
  replace wild_case_compare with my_wildcmp which is multibyte safe function