Bug #15518 Reusing a stmt that has failed during prepare does not clear error

- Additional patch removing check for mysql_errno on already closed
   mysql1


tests/mysql_client_test.c:
  No need to check mysql_errno of mysql1 which has already been closed.

tests/mysql_client_test.c

@@ -12923,7 +12923,6 @@ static void test_bug15518()
   DIE_UNLESS(rc && mysql_stmt_errno(stmt));
 
   mysql_stmt_close(stmt);
-  DIE_UNLESS(mysql_errno(mysql1));
 }