When searching for a specific filename on a case-insensitive filesystem
we first try with stat(). If stat() does find the file we currently
return the requested filename back.

That presents an issue when the application cares about the casing of the
actual file stored on-disk. Specifically, NtQueryDirectoryFile is
supposed to return the actual filename with correct casing.

One possible solution to the issue, without having to resort to manually
scanning the directory entries, is to make use of the OS X getattrlist()
function, since it can return the filename stored on the filesystem.