BUG#38290 valgrind warnings in binlog_base64_flag

The problem was because the event allocated in mysql_client_binlog_statement
was not freed when an error occured while applying the event.

sql/sql_binlog.cc:
  Delete the event if apply it failed

sql/sql_binlog.cc

@@ -208,6 +208,7 @@ void mysql_client_binlog_statement(THD* thd)
 #if !defined(MYSQL_CLIENT) && defined(HAVE_REPLICATION)
       if (apply_event_and_update_pos(ev, thd, thd->rli_fake, FALSE))
       {
+        delete ev;
         /*
           TODO: Maybe a better error message since the BINLOG statement
           now contains several events.