One more minor addition to ProcessBuilder

[David M. Lloyd]

Roger & co.:

Since you're already on the topic of manipulating pipes, I thought I'd 
mention one very small yet very useful potential enhancement.

It would be very handy to be able to specify a NULL/bit-bucket 
source/destination for pipes.  For the target process' input, the user 
can generally (I believe) just close the stream, but for output, there 
isn't really a good option.  While this is possible to achieve by 
redirecting to /dev/null on UNIX-likes and NUL (iirc) on Windows, having 
to do platform detection to decide where this device is seems overly 
cumbersome.

Having a ProcessBuilder.Redirect#DISCARD or similar would be quite 
useful, and should be fairly straightforward I think.
--
- DML