Root directory enumeration is broken on develop

[rstarkov]

Try this: new DirectoryInfo(@"C:\").GetDirectories().Count three times in a row. The first two times it's correct; the third time it's one fewer than it should be.

The reason for this appears to be the addition of an ERROR_NO_MORE_FILES check on this branch. Sometimes FindFirstFileEx sets this when enumerating the root drive. Hopefully not just on my system.