Avoid collisions between parallel installations of Cygwin

[Earnie Boyd]

Quoting Corinna Vinschen <corinna-cygwin@cygwin.com>:

>
> Does it hurt?  No.  There's only one such entry per installation path.
> Your thumb drive, typically using the same drive letter every time
> it's used on a machine, will result in one entry.
>

Too bad.  Really I want to leave zero dust when the thumb drive is removed.

--
Earnie