Imported Upstream version 4.3.2.467

Former-commit-id: 9c2cb47f45fa221e661ab616387c9cda183f283d

external/referencesource/mscorlib/system/io/longpath.cs

@@ -482,11 +482,9 @@ namespace System.IO {
 
             int lengthRoot = LongPath.GetRootLength(fullPath); 
 
-#if !PLATFORM_UNIX
             // For UNC paths that are only // or /// 
             if (length == 2 && Path.IsDirectorySeparator(fullPath[1]))
                 throw new IOException(Environment.GetResourceString("IO.IO_CannotCreateDirectory", path));
-#endif // !PLATFORM_UNIX
 
             List<string> stackDir = new List<string>();