MDEV-10728 -- mysqlbinlog can't be input to mysql client

  String comparison with utf8_bin collation is case sensitive.
  Hence "DELIMITER" did not match with "delimiter".
  The delimiter command matching now uses my_charset_latin1.

client/mysql.cc

@@ -1094,7 +1094,7 @@ inline bool is_delimiter_command(char *name, ulong len)
     only name(first DELIMITER_NAME_LEN bytes) is checked.
   */
   return (len >= DELIMITER_NAME_LEN &&
-          !my_strnncoll(charset_info, (uchar*) name, DELIMITER_NAME_LEN,
+          !my_strnncoll(&my_charset_latin1, (uchar*) name, DELIMITER_NAME_LEN,
                         (uchar *) DELIMITER_NAME, DELIMITER_NAME_LEN));
 }
 

mysql-test/r/delimiter_command_case_sensitivity.result

+1
+1

mysql-test/t/delimiter_case_mdev_10728.sql

+DeLiMiTeR A;
+SELECT 1 A;
+delimiter ;

mysql-test/t/delimiter_command_case_sensitivity.test

+# MDEV-10728
+--exec $MYSQL --default-character-set=binary < "t/delimiter_case_mdev_10728.sql"