Additional fix for bug N26402:

An attempt to open file with name '????????.frm'
can produce different errors:
- ER_NO_SUCH_TABLE on Unix
- ER_FILE_NOT_FOUND on Windows
because QUESTION MARK has special meaning on Windows.
Make sure that any of these two errors happens.

mysql-test/r/show_check.result

@@ -753,5 +753,5 @@ Tables_in_test	Table_type
 drop table `été`;
 set names latin1;
 show columns from `#mysql50#????????`;
-ERROR 42S02: Table 'test.#mysql50#????????' doesn't exist
+Got one of the listed errors
 End of 5.1 tests

mysql-test/t/show_check.test

@@ -596,7 +596,7 @@ set names latin1;
 #
 # Bug#26402 Server crashes with old-style named table
 #
---error ER_NO_SUCH_TABLE
+--error ER_NO_SUCH_TABLE,ER_FILE_NOT_FOUND
 show columns from `#mysql50#????????`;
 
 --echo End of 5.1 tests