Some function results and out parameters were not being tested.

ntdll: In find_file_in_dir(), don't test directory entries' short names if the target name isn't a short name.

hash_short_file_name() will always create a short name of at least 8 characters
with the 5th being a tilde (~).  If the target name isn't of that form, then it
can never match any short name constructed from the directory entries.