Don't throw an error after checking the first and the second arguments.
Continue with checking the third and higher arguments and if some of
them is stronger according to coercibility rules,
then this argument's collation is set as result collation.


mysql-test/r/ctype_collate.result:
  test result
mysql-test/t/ctype_collate.test:
  test case
sql/item.cc:
  Don't throw an error after checking the first and the second arguments.
  Continue with checking the third and higher arguments and if some of
  them is stronger according to coercibility rules,
  then this argument's collation is set as result collation.