sys: FspFsvolQueryDirectoryCopy: add missing continue

A single line change in FspFsvolQueryDirectoryCopy fixes GitHub issue #475.
This commit also includes a test for detecting duplicate directory entries.
Credit for the investigation and reproduction of this issue goes to GitHub
user @hach-que.

src/sys/dirctl.c

@@ -205,6 +205,7 @@ static NTSTATUS FspFsvolQueryDirectoryCopy(
                     ASSERT(sizeof(UINT64) == DirectoryMarker->Length);
                     DirectoryMarkerFound = DirectoryNextOffset == *(PUINT64)DirectoryMarker->Buffer;
                 }
+                continue;
             }
 
             /* CopyLength is the same as FileName.Length except on STATUS_BUFFER_OVERFLOW */